Nouns denoting natural phenomena

an optical phenomenon resulting from the failure of a lens or mirror to produce a good image
a hypothetical organic phenomenon by which living organisms are created from nonliving matter
the wearing down of rock particles by friction due to water or wind or ice
absorption band
a dark band in the spectrum of white light that has been transmitted through a substance that exhibits absorption at selective wavelengths
absorption spectrum
the spectrum of electromagnetic radiation that has passed through a medium that absorbed radiation of certain wavelengths
an electric current that reverses direction sinusoidally
acoustic impedance
opposition to the flow of sound through a surface; acoustic resistance is the real component of acoustic impedance and acoustic reactance is the imaginary component
acoustic phenomenon
a physical phenomenon associated with the production or transmission of sound
acoustic projection
the acoustic phenomenon that gives sound a penetrating quality
acoustic spectrum
the distribution of energy as a function of frequency for a particular sound source
actinic radiation
electromagnetic radiation that can produce photochemical reactions
action spectrum
the efficiency with which electromagnetic radiation produces a photochemical reaction plotted as a function of the wavelength of the radiation
activation energy
the energy that an atomic system must acquire before a process (such as an emission or reaction) can occur
adhesive friction
the friction between a body and the surface on which it moves (as between an automobile tire and the road)
life sustained in the presence of air or oxygen
aerodynamic force
forces acting on airfoils in motion relative to the air (or other gaseous fluids)
aerodynamic lift
the component of the aerodynamic forces acting on an airfoil that opposes gravity
a cloud of solid or liquid particles in a gas
(immunology) the attraction between an antigen and an antibody
the force attracting atoms to each other and binding them together in a molecule
any result that follows its cause after an interval
a glow sometimes seen in the sky after sunset
the consequences of an event (especially a catastrophic event)
air current
air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure
air hole
a local region of low pressure or descending air that causes a plane to lose height suddenly
air pressure
the pressure exerted by the atmosphere
a slight wind (usually refreshing)
a relatively well-defined prevailing wind
the flow of air that is driven backwards by an aircraft propeller
the phenomenon of an element existing in two or more physical forms
alluvial cone
a fan-shaped deposit where a fast flowing stream flattens out
the phenomenon of sediment or gravel accumulating
the rising of a body of water and its overflowing onto normally dry land
alpha radiation
the radiation of alpha particles during radioactive decay
alpha rhythm
the normal brainwave in the electroencephalogram of a person who is awake but relaxed; occurs with a frequency of 8-12 hertz
alternation of generations
the alternation of two or more different forms in the life cycle of a plant or animal
alternative energy
energy derived from sources that do not use up natural resources or harm the environment
the strength of an electrical current measured in amperes
amplitude distortion
distortion that occurs when the output signal does not have a linear relation to the input signal
angular acceleration
(physics) the rate of change of the angular velocity of a rotating body
angular velocity
(physics) the rate of change of the angular position of a rotating body; usually expressed in radians per second or radians per minute
annual parallax
the parallax of a celestial body using two points in the earth's orbit around the sun as the baseline
annual ring
an annual formation of wood in plants as they grow
magnetic field creates parallel but opposing spins; varies with temperature
winds blowing from west to east and lying above the trade winds in the tropics
wind in the upper atmosphere blowing above but in the opposite direction from the trade winds
a type of cell death in which the cell uses specialized cellular machinery to kill itself; a cell suicide mechanism that enables metazoans to control cell number and eliminate cells that threaten the animal's survival
apparent motion
an optical illusion of motion produced by viewing a rapid succession of still pictures of a moving object
electrical conduction through a gas in an applied electric field
arterial pressure
the pressure of the circulating blood on the arteries
atmospheric condition
the atmospheric conditions that comprise the state of the atmosphere in terms of temperature and wind and clouds and precipitation
atmospheric electricity
electrical discharges in the atmosphere
atmospheric phenomenon
a physical phenomenon associated with the atmosphere
atomic energy
the energy released by a nuclear reaction
atomic power
nuclear energy regarded as a source of electricity for the power grid (for civilian use)
atomic spectrum
(physics) a spectrum of radiation caused by electron transitions within an atom; the series of spectrum lines is characteristic of the element
the force by which one object attracts another
the outermost region of the sun's atmosphere; visible as a white halo during a solar eclipse
an atmospheric phenomenon consisting of bands of light caused by charged solar particles following the earth's magnetic lines of force
aurora australis
the aurora of the southern hemisphere
aurora borealis
the aurora of the northern hemisphere
self-induced fluorescence
bad luck
an unpredictable outcome that is unfortunate
ballistic trajectory
the trajectory of an object in free flight
bandwagon effect
the phenomenon of a popular trend attracting even greater popularity
barometric pressure
atmospheric pressure as indicated by a barometer
a column of light (as from a beacon)
a group of nearly parallel lines of electromagnetic radiation
a single pulsation of an oscillation produced by adding two waves of different frequencies; has a frequency equal to the difference between the two oscillations
beta radiation
radiation of beta particles during radioactive decay
beta rhythm
the normal brainwave in the encephalogram of a person who is awake and alert; occurs with a frequency between 12 and 30 hertz
binding energy
the energy required to separate particles from a molecule or atom or nucleus; equals the mass defect
electric phenomena in animals or plants
characteristic life processes and phenomena of living organisms
luminescence produced by physiological processes (as in the firefly)
splitting a ray into two parallel rays polarized perpendicularly
a dry cold north wind in southeastern France
blackbody radiation
the electromagnetic radiation that would be radiated from an ideal black body; the distribution of energy in the radiated spectrum of a black body depends only on temperature and is determined by Planck's radiation law
a strong current of air
a storm with widespread snowfall accompanied by strong winds
blood pressure
the pressure of the circulating blood against the walls of the blood vessels; results from the systole of the left ventricle of the heart; sometimes measured for a quick evaluation of a person's health
a powdery deposit on a surface
blue jet
atmospheric discharges (lasting 10 msec) bursting from the tops of giant storm clouds in blue cones that widen as they flash upward
a violent gusty wind
an especially luminous meteor (sometimes exploding)
a discharge of lightning accompanied by thunder
an electrical force linking atoms
a wind that blows from the north
boundary layer
the layer of slower flow of a fluid past a surface
brain death
death when respiration and other reflexes are absent; consciousness is gone; organs can be removed for transplantation before the heartbeat stops
brain wave
(neurophysiology) rapid fluctuations of voltage between parts of the cerebral cortex that are detectable with an electroencephalograph
a natural consequence of development
breaking point
the degree of tension or stress at which something breaks
a slight movement of the air
the shattering or crushing effect of a sudden release of energy as in an explosion
Brownian movement
the random motion of small particles suspended in a gas or liquid
brush discharge
discharge between electrodes creating visible streamers of ionized particles
butterfly effect
the phenomenon whereby a small change at one place in a complex system can have large effects elsewhere, e.g., a butterfly flapping its wings in Rio de Janeiro might change the weather in Chicago
a secondary and sometimes unexpected consequence
wind moving at less than 1 knot; 0 on the Beaufort scale
candle flame
the light provided by a burning candle
an electrical phenomenon whereby an electric charge is stored
a phenomenon associated with surface tension and resulting in the elevation or depression of liquids in capillaries
a radio wave that can be modulated in order to transmit a signal
catabatic wind
a wind caused by the downward motion of cold air
a sudden violent change in the earth's surface
cathode ray
a beam of electrons emitted by the cathode of an electrical discharge tube
cell death
(physiology) the normal degeneration and death of living cells (as in various epithelial cells)
centrifugal force
the outward force on a body moving in a curved path around another body
centripetal force
the inward force on a body moving in a curved path around another body
chain lightning
a form of lightning that moves rapidly in a zigzag path with one end divided (fork-like)
champion lode
the main vein of ore in a deposit
an unknown and unpredictable phenomenon that causes an event to result one way rather than another
the result of alteration or modification
the formless and disordered state of matter before the creation of the cosmos
the quantity of unbalanced electricity in a body (either positive or negative) and construed as an excess or deficiency of electrons
chatter mark
marks on a glaciated rock caused by the movement of a glacier
chemical energy
that part of the energy in a substance that can be released by a chemical reaction
chemical phenomenon
any natural phenomenon involving chemistry (as changes to atoms or molecules)
luminescence resulting from a chemical reaction as the oxidation of luciferin in fireflies
a warm dry wind blowing down the eastern slopes of the Rockies
the irregular motion of waves (usually caused by wind blowing in a direction opposite to the tide)
chromatic aberration
an optical aberration in which the image has colored fringes
movement through a circuit; especially the movement of blood through the heart and blood vessels
any collection of particles (e.g., smoke or dust) or gases that is visible
a heavy rain
(cosmology) the cooled remnant of the hot big bang that fills the entire universe and can be observed today with an average temperature of about 2.725 kelvin
coattails effect
(politics) the consequence of one popular candidate in an election drawing votes for other members of the same political party
(physics) the intermolecular force that holds together the molecules in a solid or liquid
cold front
the front of an advancing mass of colder air
cold wave
a wave of unusually cold weather
cold weather
a period of unusually cold weather
color force
(physics) the interaction that binds protons and neutrons together in the nuclei of atoms; mediated by gluons
color spectrum
the distribution of colors produced when light is dispersed by a prism
compartment pressure
the air pressure maintained in an air-tight compartment (as in an aircraft)
atmospheric moisture that has condensed because of cold
a material's capacity to conduct electricity; measured as the reciprocal of electrical resistance
the transmission of heat or electricity or sound
a phenomenon that follows and is caused by some previous phenomenon
continental drift
the gradual movement and formation of continents (as described by plate tectonics)
coordinate bond
a covalent bond in which both electrons are provided by one of the atoms
Coriolis effect
(physics) an effect whereby a body moving in a rotating frame of reference experiences the Coriolis force acting perpendicular to the direction of motion and to the axis of rotation; on Earth the Coriolis effect deflects moving bodies to the right in the northern hemisphere and to the left in the southern hemisphere
Coriolis force
(physics) a force due to the earth's rotation; acts on a body in motion (airplane or projectile) in a rotating reference frame; in a rotating frame of reference Newton's second law of motion can be made to apply if in addition to the real forces acting on a body a Coriolis force and a centrifugal force are introduced
one or more circles of light seen around a luminous object
corpuscular radiation
a stream of atomic or subatomic particles that may be charged positively (e.g. alpha particles) or negatively (e.g. beta particles) or not at all (e.g. neutrons)
corpuscular-radiation pressure
the minute pressure exerted on a surface normal to the direction of propagation of a wave
cosmic dust
clouds of particles or gases occurring throughout interstellar space
cosmic radiation
radiation coming from outside the solar system
cosmic ray
highly penetrating ionizing radiation of extraterrestrial origin; consisting chiefly of protons and alpha particles; collision with atmospheric particles results in rays and particles of many kinds
a faint spot of light in the night sky that appears directly opposite the position of the sun; a reflection of sunlight by micrometeoric material in space
covalent bond
a chemical bond that involves sharing a pair of electrons between atoms in a molecule
a side bond that links two adjacent chains of atoms in a complex molecule
wind blowing across the path of a ship or aircraft
the formation of crystals
current electricity
a flow of electric charge
a flow of electricity through a conductor
a violent rotating windstorm
the circulation of cytoplasm within a cell
light during the daytime
an electric current that flows in one direction steadily
the permanent end of all life functions in an organism or part of an organism
flooding caused by a tumultuous breakup of ice in a river during the spring or summer
phenomenon that occurs when a metal is being heated and there is a sudden slowing in the rate of temperature increase; slowing is caused by a change in the internal crystal structure of the metal
the organic phenomenon of rotting
(biology) release of material by splitting open of an organ or tissue; the natural bursting open at maturity of a fruit or other reproductive body to release seeds or spores or the bursting open of a surgically closed wound
delta rhythm
the normal brainwave in the encephalogram of a person in deep dreamless sleep; occurs with high voltage and low frequency (1 to 4 hertz)
an appreciable consequence (especially a lessening)
a loss of polarity or polarization
loss of bits of outer skin by peeling or shedding or coming off in scales
phenomenon exhibited by materials like copper or bismuth that become magnetized in a magnetic field with a polarity opposite to the magnetic force; unlike iron they are slightly repelled by a magnet
diamond dust
small crystals of ice
passage of blood cells (especially white blood cells) through intact capillary walls and into the surrounding tissue
diastolic pressure
the blood pressure (as measured by a sphygmomanometer) after the contraction of the heart while the chambers of the heart refill with blood
pleochroism of a crystal so that it exhibits two different colors when viewed from two different directions
dielectric heating
heating of an insulator by a high-frequency electric field
when light passes sharp edges or goes through narrow slits the rays are deflected and produce fringes of light and dark bands
alternation of sexual and asexual generations
(biology) the existence of two forms of individual within the same animal species (independent of sex differences)
(chemistry) the property of certain substances that enables them to exist in two distinct crystalline forms
dipole moment
the moment of a dipole
a change (usually undesired) in the waveform of an acoustic or analog electrical signal; the difference between two measurements of a signal (as between the input and output signal)
diurnal parallax
the parallax of a celestial body using two points on the surface of the earth as the earth rotates
a belt of calms and light winds between the northern and southern trade winds of the Atlantic and Pacific
the organic phenomenon in which one of a pair of alleles present in a genotype is expressed in the phenotype and the other allele of the pair is not
domino effect
the consequence of one event setting off a chain of similar events (like a falling domino causing a whole row of upended dominos to fall)
Doppler effect
change in the apparent frequency of a wave as observer and source move toward or away from each other
double bond
a covalent bond in which two pairs of electrons are shared between two atoms
a strong downward air current
the falling to earth of any form of water (rain or snow or hail or sleet or mist)
a current of air (usually coming into a chimney or room or vehicle)
the phenomenon of resistance to motion through a fluid
a force that moves something along
very light rain; stronger than mist but less than a shower
dust cloud
a cloud of dust suspended in the air
dust devil
a miniature whirlwind strong enough to whip dust and leaves and litter into the air
dust storm
a windstorm that lifts up clouds of dust or sand
east wind
a wind from the east
El Nino
(oceanography) a warm ocean current that flows along the equator from the date line and south off the coast of Ecuador at Christmas time
El Nino southern oscillation
a more intense El Nino that occurs every few years when the welling up of cold nutrient-rich water does not occur; kills plankton and fish and affects weather patterns
elan vital
(biology) a hypothetical force (not physical or chemical) once thought by Henri Bergson to cause the evolution and development of organisms
the reciprocal of capacitance
elastic energy
potential energy that is stored when a body is deformed (as in a coiled spring)
electric dipole moment
the dipole moment in an electric dipole
electric field
a field of force surrounding a charged particle
electric potential
the difference in electrical charge between two points in a circuit expressed in volts
electric power
the product of voltage and current
electric resistance
a material's opposition to the flow of electric current; measured in ohms
electric storm
a storm resulting from strong rising air currents; heavy rain or hail along with thunder and lightning
electrical conduction
the passage of electricity through a conductor
electrical disturbance
electrical signals produced by unwanted sources (atmospherics or receiver noise or unwanted transmitters)
electrical energy
energy made available by the flow of electric charge through a conductor
electrical line of force
a line of force in an electrical field
electrical phenomenon
a physical phenomenon involving electricity
a physical phenomenon associated with stationary or moving electrons and protons
electromagnetic interaction
an interaction between charged elementary particles that is intermediate in strength between the strong and weak interactions; mediated by photons
electromagnetic radiation
radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge
electromagnetic spectrum
the entire frequency range of electromagnetic waves
magnetism produced by an electric current
electromotive force
the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts
electrostatic bond
a chemical bond in which one atom loses an electron to form a positive ion and the other atom gains an electron to form a negative ion
electrostatic charge
the electric charge at rest on the surface of an insulated body (which establishes and adjacent electrostatic field)
electrostatic field
electric field associated with static electric charges
violent or severe weather (viewed as caused by the action of the four elements)
an acronym for emissions of light and very low frequency perturbations due to electromagnetic pulse sources; extremely bright extremely short (less than a msec) electrical flashes forming a huge ring (up to 400 km diameter) in the ionosphere
emission spectrum
spectrum of electromagnetic radiation emitted by a self-luminous source
a geological phenomenon below the surface of the earth
any source of usable power
energy level
a definite stable energy that a physical system can have; used especially of the state of electrons in atoms or molecules
(physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs
something used to achieve a purpose
a secondary phenomenon that is a by-product of another phenomenon
equatorial current
any of the ocean currents that flow westward at the equator
equinoctial storm
a violent rainstorm near the time of an equinox
even chance
an unpredictable phenomenon
a phenomenon located at a single point in space-time; the fundamental observational entity in relativity theory
evoked potential
the electrical response of the central nervous system produced by an external stimulus
chemical process in which one atom or ion or group changes places with another
the peeling off in flakes or scales of bark or dead skin
(neurophysiology) phenomenon that occurs when two or more neural impulses that alone are not enough to trigger a response in a neuron combine to trigger an action potential
a bright spot on a planet
a large bright spot on the sun's photosphere occurring most frequently in the vicinity of sunspots
fair weather
moderate weather; suitable for outdoor activities
any adverse and unwanted secondary effect
fata morgana
a mirage in the Strait of Messina (attributed to the Arthurian sorcerer Morgan le Fay)
a phenomenon in ferrites where there can be incomplete cancellation of antiferromagnetic arranged spins giving a net magnetic moment
phenomenon exhibited by materials like iron (nickel or cobalt) that become magnetized in a magnetic field and retain their magnetism when the field is removed
field line
an imaginary line in a field of force; direction of the line at any point is the direction of the force at that point
the space around a radiating body within which its electromagnetic oscillations can exert force on another similar body not in contact with it
fine spray
precipitation in very small drops
fine structure
the presence of groups of closely spaced spectrum lines observed in the atomic spectrum of certain elements
the light of a fire (especially in a fireplace)
a storm in which violent winds are drawn into the column of hot air rising over a severely bombed area
a crystal of snow
am unwanted reflection in an optical system (or the fogging of an image that is caused by such a reflection)
a sudden eruption of intense high-energy radiation from the sun's surface; associated with sunspots and radio interference
flash flood
a sudden local flood of great volume and short duration
an unintended electric discharge (as over or around an insulator)
the path followed by an object moving through space
the phenomenon of floating (remaining on the surface of a liquid without sinking)
a wall of water rushing ahead of the flood
a stroke of luck
light emitted during absorption of radiation of some other (invisible) wavelength
a light brief snowfall and gust of wind (or something resembling that)
the lines of force surrounding a permanent magnet or a moving charged particle
focal point
a point of convergence of light (or other radiation) or a point from which it diverges
a warm dry wind that blows down the northern slopes of the Alps
droplets of water vapor suspended in the air near the ground
a large mass of fog on the sea (as seen from a distance)
food chain
(ecology) a community of organisms where each member is eaten in turn by another member
food cycle
(ecology) a community of organisms where there are several interrelated food chains
food pyramid
(ecology) a hierarchy of food chains with the principal predator at the top; each level preys on the level below
(physics) the influence that produces a change in a physical quantity
force per unit area
the force applied to a unit area of surface; measured in pascals (SI unit) or in dynes (cgs unit)
an unknown and unpredictable phenomenon that leads to a favorable outcome
weather cold enough to cause freezing
fresh breeze
wind moving 19-24 knots; 5 on the Beaufort scale
fresh gale
wind moving 39-46 knots; 8 on the Beaufort scale
friar's lantern
a pale light sometimes seen at night over marshy ground
the resistance encountered when one body is moved in contact with another
one of the light or dark bands produced by the interference and diffraction of light
(meteorology) the atmospheric phenomenon created at the boundary between two different air masses
frost heave
upthrust of ground or pavement caused by the freezing of moist soil
a cloud of fine particles suspended in a gas
fundamental interaction
(physics) the transfer of energy between elementary particles or between an elementary particle and a field or between fields; mediated by gauge bosons
a strong wind moving 45-90 knots; force 7 to 10 on Beaufort scale
electricity produced by chemical action
gamma radiation
electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength
the localized death of living cells (as from infection or the interruption of blood supply)
gas pressure
the pressure exerted by a gas
light yielded by the combustion of illuminating gas
gene expression
conversion of the information encoded in a gene first into messenger RNA and then to a protein
gentle breeze
wind moving 8-12 knots; 3 on the Beaufort scale
geological phenomenon
a natural phenomenon involving the structure or composition of the earth
geothermal energy
energy derived from the heat in the interior of the earth
a steady even light without flames
the amount of electromagnetic radiation leaving or arriving at a point on a surface
the phenomenon of light emission by a body as its temperature is raised
(physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface
gravitational field
a field of force surrounding a body of finite mass
gravitational interaction
a weak interaction between particles that results from their mass; mediated by gravitons
(spaceflight) a trajectory that passes close to a planetary body in order to gain energy from its gravitational field
greenhouse effect
warming that results when solar radiation is trapped by the atmosphere; caused by atmospheric gases that allow sunshine to pass through but absorb heat that is radiated back from the warmed surface of the earth
the phenomenon of vitality and freshness being restored
ground effect
apparent increase in aerodynamic lift experienced by an aircraft flying close to the ground
ground wave
a radio wave propagated on or near the earth's surface
Gulf stream
a warm ocean current that flows from the Gulf of Mexico northward through the Atlantic Ocean
gun smoke
smoke created by the firing of guns
precipitation of ice pellets when there are strong rising air currents
a storm during which hail falls
a greyish light (as at dawn or dusk or in dim interiors)
a circle of light around the sun or moon
a dusty wind from the Sahara that blows toward the western coast of Africa during the winter
the consequence of an effort or activity
atmospheric moisture or dust or smoke that causes reduced visibility
the pressure exerted by a fluid
head sea
a sea in which the waves are running directly against the course of the ship
wind blowing opposite to the path of a ship or aircraft
heat of condensation
heat liberated by a unit mass of gas at its boiling point as it condenses into a liquid
heat of dissociation
the heat required for a fluid substance to break up into simpler constituents
heat of formation
the heat evolved or absorbed during the formation of one mole of a substance from its component elements
heat of fusion
heat absorbed by a unit mass of a solid at its melting point in order to convert the solid into a liquid at the same temperature
heat of solidification
heat liberated by a unit mass of liquid at its freezing point when it solidifies
heat of solution
the heat evolved or absorbed when one mole of a substance is dissolved in a large volume of a solvent
heat of sublimation
heat absorbed by a unit mass of material when it changes from a solid to a gaseous state
heat of transformation
heat absorbed or radiated during a change of phase at a constant temperature and pressure
heat of vaporisation
heat absorbed by a unit mass of a material at its boiling point in order to convert the material into a gas at the same temperature
heat ray
a ray that produces a thermal effect
heat wave
a wave of unusually hot weather
a form of energy that is transferred by a difference in temperature
Hertzian wave
a former name for a radio wave; an electromagnetic wave of radio frequency generated by oscillations in an electric circuit
high beam
the beam of a car's headlights that provides distant illumination
high wind
a very strong wind
condition in which the cells of one tissue can survive in the presence of cells of another tissue
horizontal parallax
the maximum parallax observed when the celestial body is at the horizon
hot weather
a period of unusually high temperatures
a severe tropical cyclone usually with heavy rains and winds moving at 63-136 knots (12 on the Beaufort scale)
electricity produced by water power
hydrogen bond
a chemical bond consisting of a hydrogen atom between two electronegative atoms (e.g., oxygen or nitrogen) with one side be a covalent bond and the other being an ionic bond
hydrostatic head
the pressure at a given point in a liquid measured in terms of the vertical height of a column of the liquid needed to produce the same pressure
the lagging of an effect behind its cause; especially the phenomenon in which the magnetic induction of a ferromagnetic material lags behind the changing magnetic field
ice fog
a dense winter fog containing ice particles
ice storm
a storm with freezing rain that leaves everything glazed with ice
a forceful consequence; a strong effect
the striking of a light beam on a surface
an electrical phenomenon whereby an electromotive force (EMF) is generated in a closed circuit by a change in the flow of current
(physics) the tendency of a body to maintain its state of rest or uniform motion unless acted upon by an external force
the effect of one thing (or person) on another
infrared ray
a ray of infrared radiation; produces a thermal effect (as from an infrared lamp)
infrared spectrum
the spectrum of infrared radiation
electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves
incident solar radiation
instantaneous sound pressure
the difference between the instantaneous pressure at a point in a sound field and the average pressure at that point
interfacial surface tension
surface tension at the surface separating two non-miscible liquids
reciprocal reflection between two reflecting surfaces
a signal that temporarily stops the execution of a program so that another procedure can be carried out
the layer of air near the earth is cooler than an overlying layer
ion beam
a beam of ions moving in the same direction at the same speed
ionizing radiation
high-energy radiation capable of producing ionization in substances through which it passes
ionospheric wave
a sky wave that is reflected by the ionosphere
pressure exerted by the fluids inside the eyeball; regulated by resistance to the outward flow of aqueous humor
jet propulsion
propulsion by means of the discharge of a jet of fluid toward the rear
jet stream
a high-speed high-altitude airstream blowing from west to east near the top of the troposphere; has important effects of the formation of weather fronts
electric current
the mechanical energy that a body has by virtue of its motion
an oppressively hot southerly wind from the Sahara that blows across Egypt in the spring
knock-on effect
a secondary or incidental effect
Kuroshio current
a warm ocean current that flows northeastwardly off the coast of Japan into the northern Pacific ocean
laminar flow
nonturbulent streamline flow in parallel layers (laminae)
light from a lamp
oppressively still air
laser beam
a beam of light generated by a laser
an easterly wind in the western Mediterranean area
the mechanical advantage gained by being in a position to use a lever
the phenomenon of a person or thing rising into the air by apparently supernatural means
the organic phenomenon that distinguishes living organisms from nonliving ones
life cycle
a series of stages through which an organism passes between recurrences of a primary stage
light air
wind moving 1-3 knots; 1 on the Beaufort scale
light breeze
wind moving 4-7 knots; 2 on the Beaufort scale
(physics) electromagnetic radiation that can produce a visual sensation
abrupt electric discharge from cloud to cloud or from cloud to earth accompanied by the emission of light
a single frequency (or very narrow band) of radiation in a spectrum
line spectrum
a spectrum in which energy is concentrated at particular wavelengths; produced by excited atoms and ions as they fall back to a lower energy level
line squall
a squall advancing along a front that forms a definite line
the power output of a generator or power plant
a deposit of valuable ore occurring within definite boundaries separating it from surrounding rocks
long wave
a radio wave with a wavelength longer than a kilometer (a frequency below 300 kilohertz)
Lorentz force
the force experienced by a point charge moving along a wire that is in a magnetic field; the force is at right angles to both the current and the magnetic field
low beam
the beam of a car's headlights that provides illumination for a short distance
light not due to incandescence; occurs at low temperatures
luminous energy
the energy associated with visible light
a cooler darker spot appearing periodically on the sun's photosphere; associated with a strong magnetic field
magnetic attraction
attraction for iron; associated with electric currents as well as magnets; characterized by fields of force
magnetic dipole moment
(physics) a current loop gives rise to a magnetic field characteristic of a magnetic dipole
magnetic line of force
a line of force in a magnetic field
magnetic moment
the torque exerted on a magnet or dipole when it is placed in a magnetic field
magnetic resonance
resonance of electrons or atoms or molecules or nuclei to radiation frequencies as a result of space quantization in a magnetic field
magnetomotive force
the force that produces magnetic flux
the magnetic field of a planet; the volume around the planet in which charged particles are subject more to the planet's magnetic field than to the solar magnetic field
mass defect
the amount by which the mass of an atomic nucleus is less than the sum of the masses of its constituent particles
mass spectrum
a distribution of ions as shown by a mass spectrograph or a mass spectrometer
mechanical energy
energy in a mechanical form
mechanical phenomenon
a physical phenomenon associated with the equilibrium or motion of objects
medium wave
a radio wave with a wavelength between 100 and 1000 meters (a frequency between 300 kilohertz and 3000 kilohertz)
metallic bond
a chemical bond in which electrons are shared over many nuclei and electronic conduction occurs
after death the soul begins a new cycle of existence in another human body
meteor shower
a transient shower of meteors when a meteor swarm enters the earth's atmosphere
a streak of light in the sky at night that results when a meteoroid hits the earth's atmosphere and air friction causes the meteoroid to melt or vaporize or explode
a short electromagnetic wave (longer than infrared but shorter than radio waves); used for radar and microwave ovens and for transmitting telephone, facsimile, video and data
microwave spectrum
the part of the electromagnetic spectrum corresponding to microwaves
midnight sun
the sun visible at midnight (inside the Arctic or Antarctic Circles)
an optical illusion in which atmospheric refraction by a layer of hot air distorts or inverts reflections of distant objects
a thin fog with condensation near the ground
a strong north wind that blows in France during the winter
mock sun
a bright spot on the parhelic circle; caused by diffraction by ice crystals
moderate breeze
wind moving 13-18 knots; 4 on the Beaufort scale
moderate gale
wind moving 32-38 knots; 7 on the Beaufort scale
a turning force produced by an object acting at a distance (or a measure of that force)
moment of a couple
given two equal and opposite forces, the product of the force and the distance between them
moment of inertia
the tendency of a body to resist angular acceleration
a seasonal wind in southern Asia; blows from the southwest (bringing rain) in summer and from the northeast in winter
any wind that changes direction with the seasons
the light of the Moon
moon ray
a ray of moonlight
a large cloud of rubble and dust shaped like a mushroom and rising into the sky after an explosion (especially of a nuclear bomb)
mutual induction
generation of electromotive forces in each other by two adjacent circuits
localized death of muscle cell fibers
natural phenomenon
all phenomena that are not artificial
negative charge
having a surplus of electrons; having a lower electric potential
neutron radiation
radiation of neutrons (as by a neutron bomb)
resonance of protons to radiation in a magnetic field
Noah and the Flood
(Biblical) the great deluge that is said in the Book of Genesis to have occurred in the time of Noah; it was brought by God upon the earth because of the wickedness of human beings
a storm blowing from the northeast
North Equatorial Current
an equatorial current that flows west across the Pacific just north of the equator
northwest wind
a wind from the northwest
nuclear propulsion
the use of a nuclear reactor either to produce electricity to power an engine (as in a nuclear submarine) or to directly heat a propellant (as in nuclear rockets)
nuclear resonance
the resonance absorption of a gamma ray by a nucleus identical to the nucleus that emitted the gamma ray
nuclear winter
a long period of darkness and extreme cold that scientists predict would follow a full-scale nuclear war; a layer of dust and smoke in the atmosphere would cover the earth and block the rays of the sun; most living organisms would perish
occluded front
(meteorology) a composite front when colder air surrounds a mass of warm air and forces it aloft
ocean current
the steady flow of surface ocean water in a prevailing direction
the ohmic resistance of a conductor
oil pressure
pressure that keeps oil on the moving parts of an internal-combustion engine
the phenomenon of not permitting the passage of electromagnetic radiation
optical illusion
an optical phenomenon that results in a false or deceptive visual impression
optical opacity
opacity to light
optical phenomenon
a physical phenomenon related to or involving light
organic phenomenon
(biology) a natural phenomenon involving living plants and animals
osmotic pressure
(physical chemistry) the pressure exerted by a solution necessary to prevent osmosis into that solution when it is separated from the pure solvent by a semipermeable membrane
a transient air pressure greater than the surrounding atmospheric pressure
too much strain
the mechanical energy that a body has by virtue of its position; stored energy
the apparent displacement of an object as seen from two different points that are not on a line with the object
materials like aluminum or platinum become magnetized in a magnetic field but it disappears when the field is removed
parhelic circle
a luminous halo parallel to the horizon at the altitude of the sun; caused by ice crystals in the atmosphere
particle beam
a collimated flow of particles (atoms or electrons or molecules)
pea soup
a heavy thick yellow fog
peptide bond
the primary linkage of all protein structures; the chemical bond between the carboxyl groups and amino groups that unites a peptide
(physics) a secondary influence on a system that causes it to deviate slightly
Peruvian current
a cold ocean current that flows north along the Pacific Coast of South America before turning west
a fluorescence that persists after the bombarding radiation has ceased
photochemical exchange
an exchange produced by the chemical action of radiant energy (especially light)
change in the electrical conductivity of a substance as a result of absorbing electromagnetic radiation
electricity generated by light or affected by light
an emission of photoelectrons (especially from a metallic surface)
physical phenomenon
a natural phenomenon involving the physical properties of matter and energy
piezo effect
electricity produced by mechanical pressure on certain crystals (notably quartz or Rochelle salt); alternatively, electrostatic stress produces a change in the linear dimensions of the crystal
placebo effect
any effect that seems to be a consequence of administering a placebo; the change is usually beneficial and is assumed result from the person's faith in the treatment or preconceptions about what the experimental drug was supposed to do; pharmacologists were the first to talk about placebo effects but now the idea has been generalized to many situations having nothing to do with drugs
the phenomenon of different colors appearing when certain crystals are viewed from different directions
(biology) the appearance of two or more distinctly different forms in the life cycle of some organisms
(chemistry) the existence of different kinds of crystal of the same chemical compound
the phenomenon in which waves of light or other radiation are restricted in direction of vibration
(genetics) the genetic variation within a population that natural selection can operate on
(biology) the existence of two or more forms of individuals within the same animal species (independent of sex differences)
position effect
(genetics) the effect on the expression of a gene that is produced by changing its location in a chromosome
positive charge
having a deficiency of electrons; having a higher electric potential
(physics) the rate of doing work; measured in watts (= joules/second)
prevailing westerly
the winds from the west that occur in the temperate zones of the Earth
prevailing wind
the predominant wind direction
a consequence of someone's efforts or of a particular set of circumstances
the movement of a wave through a medium
a propelling force
a short light gust of air
the force used in pulling
pulmonary circulation
circulation of blood between the heart and the lungs
a periodically recurring phenomenon that alternately increases and decreases some quantity
a means of exerting influence or gaining advantage
the force used in pushing
generation of an electric charge on certain crystals (such as tourmaline) as a result of a change in temperature
radiant energy
energy that is transmitted in the form of (electromagnetic) radiation; energy that exists in the absence of matter
energy that is radiated or transmitted in the form of rays or waves or particles
radiation field
a field that represents the energy lost from the radiator to space
radio emission
an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m
radio signal
a radio wave used to transmit and receive messages
radio spectrum
the entire spectrum of electromagnetic frequencies used for communications; includes frequencies used for radio and radar and television
opacity to X-rays or other radiation
rain shower
a brief period of precipitation
water falling in drops from vapor condensed in the atmosphere
a drop of rain
a storm with rain
opposition to the flow of electric current resulting from inductance and capacitance (rather than resistance)
(mechanics) the equal and opposite force that is produced when any force is applied to a body
a response that reveals a person's feelings or attitude
reaction propulsion
propulsion that results from the ejection at high velocity of a mass of gas to which the vehicle reacts with an equal and opposite momentum
(biology) the ability of one molecule to attach to another molecule that has a complementary shape
red shift
(astronomy) a shift in the spectra of very distant galaxies toward longer wavelengths (toward the red end of the spectrum); generally interpreted as evidence that the universe is expanding
red sprites
atmospheric electricity (lasting 10 msec) appearing as globular flashes of red (pink to blood-red) light rising to heights of 60 miles (sometimes seen together with elves)
the phenomenon of a propagating wave (light or sound) being thrown back from a surface
the change in direction of a propagating wave (light or sound) when passing from one medium to another
(medicine) an immunological response that refuses to accept substances or organisms that are recognized as foreign
(physics) opposition to magnetic flux (analogous to electric resistance)
a remote or indirect consequence of some action
the force by which bodies repel one another
any mechanical force that tends to retard or oppose motion
(computer science) the number of pixels per square inch on a computer-generated display; the greater the resolution, the better the picture
the ability of a microscope or telescope to measure the angular separation of images that are close together
a vibration of large amplitude produced by a relatively small vibration near the same frequency of vibration as the natural frequency of the resonating system
an excited state of a stable particle causing a sharp maximum in the probability of absorption of electromagnetic radiation
a result
rest energy
the energy equivalent to the mass of a particle at rest in an inertial frame of reference; equal to the rest mass times the square of the speed of light
resting potential
the potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse
rocket propulsion
reaction propulsion using stored oxygen for combustion; used where there is insufficient atmospheric oxygen
Saint Elmo's light
an electrical discharge accompanied by ionization of surrounding atmosphere
a violent hot sand-laden wind on the deserts of Arabia and North Africa
a blast of wind laden with sand
Santa Ana
a strong hot dry wind that blows in winter from the deserts of southern California toward the Pacific Coast
a light shower that falls in some locations and not others nearby
(physics) a flash of light that is produced in a phosphor when it absorbs a photon or ionizing particle
an extremely hot day
turbulent water with swells of considerable size
sea breeze
a cooling breeze from the sea (during the daytime)
sea-level pressure
the atmospheric pressure reduced by a formula to the pressure at sea level
generation of an electromotive force (EMF) in a circuit by changing the current in that circuit; usually measured in henries
good luck in making unexpected and fortunate discoveries
sex linkage
an association between genes in sex chromosomes that makes some characteristics appear more frequently in one sex than in the other
(physics) a deformation of an object in which parallel planes remain parallel but are shifted in a direction parallel to themselves
short wave
a radio wave with a wavelength less than 100 meters (a frequency greater than 3 megahertz)
an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes
skin effect
the tendency of high-frequency alternating current to distribute near the surface of a conductor
sky glow
illumination of the night sky in urban areas
sky wave
a radio wave that is reflected back to earth by the ionosphere or a communications satellite; permits transmission around the curve of the earth's surface
partially melted snow (or a mixture of rain and snow)
a stifling cloud of smoke
precipitation falling from clouds in the form of ice crystals
(genetics) genetic variation in a DNA sequence that occurs when a single nucleotide in a genome is altered; SNPs are usually considered to be point mutations that have been evolutionarily successful enough to recur in a significant proportion of the population of a species
solar energy
energy from the sun that is converted into thermal or electrical energy
solar gravity
the gravity of the sun
solar magnetic field
the magnetic field of the sun
solar parallax
the angle subtended by the mean equatorial radius of the Earth at a distance of one astronomical unit
solar prominence
large eruptions of luminous hydrogen gas that rise thousands of kilometers above the chromosphere
solar radiation
radiation from the sun
solar wind
a stream of protons moving radially from the sun
sonic barrier
the increase in aerodynamic drag as an airplane approaches the speed of sound
a strong wind from the southeast
mechanical vibrations transmitted by an elastic medium
South Equatorial Current
an equatorial current that flows west across the Pacific just south of the equator
south wind
a wind from the south
a strong wind from the southwest
specific heat
the heat required to raise the temperature of one gram of a substance one degree centigrade
an ordered array of the components of an emission or wave
speech spectrum
the average sound spectrum for the human voice
spherical aberration
an optical aberration resulting in a distorted image
(economics) any indirect effect of public expenditure
sudden violent winds; often accompanied by precipitation
squall line
a cold front along which squalls or thunderstorms are likely
the light of the stars
static electricity
electricity produced by friction
stellar parallax
the heliocentric parallax of a star
a violent weather condition with winds 64-72 knots (11 on the Beaufort scale) and precipitation and thunder and lightning
(physics) deformation of a physical body under the action of applied forces
light that streams
streamline flow
flow of a gas or liquid in which the velocity at any point is relatively steady
(physics) force that produces strain on a physical body
strong breeze
wind moving 25-31 knots; 6 on the Beaufort scale
strong gale
wind moving 47-54 knots; 9 on the Beaufort scale
a force over an area produced by a pressure difference
oppressively hot and humid weather
the rays of the sun
a ray of sunlight
a sudden emergence of the sun from behind clouds
a ray of artificial ultraviolet light from a sunray lamp
atmospheric phenomena accompanying the daily appearance of the sun
atmospheric phenomena accompanying the daily disappearance of the sun
the disappearance of electrical resistance at very low temperatures
the most powerful tornado which can create enormously devastating damage
surface tension
a phenomenon at the surface of a liquid caused by intermolecular forces
condensation of moisture on a cold surface
sympathetic vibration
(physics) vibration produced by resonance
systemic circulation
circulation that supplies blood to all the body except to the lungs
systolic pressure
the blood pressure (as measured by a sphygmomanometer) during the contraction of the left ventricle of the heart
the straight line configuration of 3 celestial bodies (as the sun and earth and moon) in a gravitational system
wind blowing in the same direction as the path of a ship or aircraft
(literary) a violent wind
(physics) a stress that produces an elongation of an elastic physical body
warm weather following a freeze; snow and ice melt
rising current of warm air
thermionic current
an electric current produced between two electrodes as a result of electrons emitted by thermionic emission
electricity produced by heat (as in a thermocouple)
theta rhythm
the normal brainwave in the encephalogram of a person who is awake but relaxed and drowsy; occurs with low frequency and low amplitude
a short rainstorm accompanied by thunder and lightning
light from a torch or torches
a localized and violently destructive windstorm occurring over land characterized by a funnel-shaped cloud extending toward the ground
a twisting force
steady winds blowing from east to west above and below the equator
a cold dry wind that blows south out of the mountains into Italy and the western Mediterranean
the spreading of the sea over land as evidenced by the deposition of marine strata over terrestrial strata
permitting the free passage of electromagnetic radiation
pleochroism of a crystal so that it exhibits three different colors when viewed from three different directions
unstable flow of a liquid or gas
turbulent flow
flow in which the velocity at any point varies erratically
the diffused light from the sky when the sun is below the horizon but its rays are refracted by the atmosphere of the earth
Tyndall effect
the phenomenon in which light is scattered by very small particles in its path; it makes a beam of light visible; the scattered light is mainly blue
a tropical cyclone occurring in the western Pacific or Indian oceans
very high frequency sound; used in ultrasonography
ultraviolet spectrum
the spectrum of ultraviolet radiation
a strong upward air current
radiation lying in the ultraviolet range; wave lengths shorter than light but longer than X rays
the phenomenon of forming chemical bonds
van der Waal's forces
relatively weak attraction between neutral atoms and molecules arising from polarization induced in each particle by the presence of other particles
vapor pressure
the pressure exerted by a vapor; often understood to mean saturated vapor pressure (the vapor pressure of a vapor in contact with its liquid form)
(astronomy) any perturbation of the mean motion or orbit of a planet or satellite (especially a perturbation of the earth's moon)
venous pressure
the pressure exerted on the walls of the veins by the circulating blood
light wispy precipitation that evaporates before it reaches the ground (especially when the lower air is low in humidity)
virtual image
a reflected optical image (as seen in a plane mirror)
vitelline circulation
circulation of blood between the embryo and the yolk sac
the phenomena associated with volcanic activity
warm front
the front of an advancing mass of warmer air
the power to do work that is latent in a head of water
a tornado passing over water and picking up a column of water and mist
a persistent and widespread unusual weather condition (especially of unusual temperatures)
wave front
all the points just reached by a wave as it propagates
weak force
(physics) an interaction between elementary particles involving neutrinos or antineutrinos that is responsible for certain kinds of radioactive decay; mediated by intermediate vector bosons
west wind
wind that blows from west to east
a more or less vertical column of air whirling around itself as it moves over the surface of the Earth
an arctic atmospheric condition with clouds over snow produce a uniform whiteness and objects are difficult to see; occurs when the light reflected off the snow equals the light coming through the clouds
whole gale
wind moving 55-63 knots; 10 on the Beaufort scale
a tendency or force that influences events
wind generation
power derived from the wind (as by windmills)
the retarding force of air friction on a moving object
a storm consisting of violent winds
(physics) a manifestation of energy; the transfer of energy from one physical system to another expressed as the product of a force and the distance through which it moves a body in the direction of that force
electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target
X-ray diffraction
the scattering of X rays by the atoms of a crystal; the diffraction pattern shows structure of the crystal
zodiacal light
a luminous tract in the sky; a reflection of sunlight from cosmic dust in the plane of the ecliptic; visible just before sunrise and just after sunset