1. Relating, referring to, or taking place in the earth's atmosphere.
2. Dependent on, caused by, or resulting from the atmosphere.
3. Giving or creating an atmosphere; such as, atmospheric music.

A term for early steam engine designs; so called because the pressure of the steam was the same as, or near, the pressure of the surrounding atmosphere.

1. The absorption of radiation by the gases and moisture in the atmosphere.
2. The reduction in energy of microwaves by gases and moisture in the atmosphere.

1. The propagation of sound through the atmosphere, which affects sound in predictable ways according to atmospheric conditions; such as, temperature and precipitation.
2. The science of sound waves in the open air.

1. A process in which the flux density of a parallel beam of energy decreases with increasing distance from the source as a result of absorption or scattering by the atmosphere.
2. The depletion of electromagnetic energy in the atmosphere because of absorption or diffusion.

A generic term for scintillation phenomena observed in light that reaches the eyes from sources lying within the earth's atmosphere.

Scintillation refers to the rapid fluctuations in the amplitude and phase of electromagnetic or acoustic waves that have propagated through a medium containing fluctuations in refractive index, such as the atmosphere.

The most common example of optical scintillation is the "twinkling" of stars observed through the atmosphere because it arises as a result of random angular scattering produced by refractive index fluctuations.

Fluctuations in the amplitude of different frequency components in the spectrum of an object can give rise to apparent changes in its color (chromatic scintillation); an example is the random red and blue twinkling of bright stars near the horizon.

Scintillation statistics have been used to study turbulence in regions ranging from the planetary boundary layer to the ionosphere, as well as interplanetary and interstellar space and it is important for astronomical imaging, optical and radio communications, laser and acoustical propagation, active and passive remote sensing, and the performance of the Global Positioning System.

1. In the earth's atmosphere, the planetary boundary layer is the air layer near the ground affected by diurnal heat, moisture, or momentum transfer to or from the surface.
2. The thin layer of air adjacent to the earth's surface, usually considered to be less than 300 feet (91 meters) high.
3. The thin layer of air adjacent to the earth's surface, extending up to the so-called anemometer level (the base of the Ekman layer [thin top layer of the sea]); within this layer the wind distribution is determined largely by the vertical temperature gradient and the nature and contours of the underlying surface, and shearing stresses are approximately constant.

1. Slowing down an object entering the atmosphere of the earth or other planet from space by using the drag exerted by air or other gas particles in the atmosphere and the action of the drag so exerted.
2. The slowing of the speed of an object as it encounters the drag of a planetary atmosphere; such as, that which is initiated or enhanced deliberately, as when landing a space vehicle.

The study of the production, transport, modification, and removal of atmospheric constituents in the troposphere and stratosphere.

The chemical constituents and abundance in the earth's atmosphere of its constituents, including nitrogen, oxygen, argon, carbon dioxide, water vapor, ozone, neon, helium, krypton, methane, hydrogen, and nitrous oxide.

The transformation of water in the air from a vapor phase to dew, fog, or a cloud.

Any device or system designed to operate movable aerodynamic control surfaces to direct a guided missile in an atmosphere dense enough for such controls to be effective and the control provided by such devices.

The vertical movement of air currents resulting from temperature variations.

1. In mechanical engineering, a cooler for fluids that uses air circulation obtained by natural convection to cool hot, fluid-filled tubes.
2. A fluids cooler that utilizes the cooling effect of ambient air surrounding hot, fluids-filled tubes.

The gradual destruction or alteration of a metal or alloy by contact with substances present in the atmosphere; such as, oxygen, carbon dioxide, water vapor and sulfur, and chlorine compounds.

The ratio of the mass of a portion of the atmosphere to the volume it occupies.

The exchange of fluid parcels between regions in the atmosphere in the apparently random motions of a scale too small to be treated by the equations of motion.

The spreading of a star image into a small spectrum as its light travels through the earth's atmosphere.

The atmosphere acts in the same way as a glass prism. The path the light takes depends to a small extent on its wavelength.

As a result, the blue light from a star seems to come from slightly closer to the zenith than the red light.

1. A refining process in which crude oil components are separated at atmosph4eric pressure by heating to temperatures of about 600-750°F and the subsequent condensing of the fractions by cooling.
2. In chemical engineering, a distillation operation conducted at atmospheric pressure, in contrast to vacuum distillation or pressure distillation.

1. Any agitation or disruption of the atmospheric steady state.
2. Any interruption of a state of equilibrium of the atmosphere.
3. An area showing signs of a developing cyclonic circulation.
4. A periodic disturbance in the fields of atmospheric variables (like surface pressure or geopotential height, temperature, or wind velocity) which may either propagate (traveling wave) or not (stationary wave).

Atmospheric waves range in spatial and temporal scale from large-scale planetary waves (Rossby waves or giant meanders, twists and turns, in high-altitude winds that are a major influence on weather) to minute sound waves.

1. A major perturbation (disturbance and trouble) of the close artificial satellite orbits caused by the resistance of the atmosphere; the secular effects are decreasing eccentricity, semidiameter (apparent radius of a celestial body when viewed as a disk from the earth), and period.
2. A critical perturbation of the orbits of closely adjacent low-orbit artificial satellites due to atmospheric resistance; the effects extending over ages of time are semidiameter, period, and decreasing eccentricity.

1. In geophysics, a layer of the troposphere in which refractive properties are such as to trap a large proportion of certain high frequency radiations.
2. A stratum of the troposphere within which the refractive index varies so as to confine within he limits of the stratum the propagation of an abnormally large proportion of any radiation of sufficiently high frequency, as in a mirage.

Atmospheric ducting is a mode of propagation of electromagnetic radiation, usually in the lower layers of the earth’s atmosphere, where the waves are bent by atmospheric refraction.

1. The atmosphere's electric field strength in volts per meter at any specified point in time and space; near the earth's surface, in fair-weather areas.

A typical datum is about 100 and the field is directed vertically in such a way as to drive positive charges downward.

2. A quantitative term indicating the electric field strength of the atmosphere at any specified point in space and time.
3. A measure, in volts per meter, of the electrical energy in a given portion of the earth's atmosphere at a given time.

1. The electrical processes occurring in the lower atmosphere, including both the intense local electrification accompanying storms and the much weaker fair-weather electrical activity over the entire globe produced by the electrified storms continuously in progress.
2. The study of electrical processes occurring within the atmosphere.
3. Electrical phenomena, regarded collectively, that occur in the earth's atmosphere.

These phenomena include not only such striking manifestations as lightning and St. Elmo's fire, but also less noticeable but more ubiquitous effects; such as, atmospheric ionization, the air–earth currents, and other quiescent electrical processes.

The existence of separated electric charges in the atmosphere is a consequence of many minor processes; such as, spray electrification, dust electrification, etc. and a few major processes including, cosmic-ray ionization, radioactive-particle ionization, and thunderstorm electrification.

The maintenance of the prevailing atmospheric electric field is now widely believed to be due to thunderstorm effects.

1. The penetration of any planetary atmosphere by any object from outer space; specifically, the penetration of the earth's atmosphere by a crewed, or uncrewed, capsule or spacecraft.
2. The penetration of human-made or natural objects from a planetary atmosphere by an object approaching from space; especially, of the earth's atmosphere by a re-entering spacecraft.

The reduction in intensity of light from an astronomical object by absorption and scattering in the earth's atmosphere.

Extinction increases when the object is closer to the horizon because of the greater thickness of atmosphere through which its light must travel.

One of the constituents of air, consisting of a gaseous mixture; primarily of nitrogen, oxygen, argon, carbon dioxide, water vapor, ozone, neon, helium, krypton, methane, hydrogen, and nitrous oxide; plus small amounts of other gases.

The atmosphere protects life on earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night.

Any atmospheric flow used to refer to the general circulation of the earth and regional movements of air around areas of high and low pressure.

On average, this circulation corresponds to large-scale wind systems arranged in several east–west belts that encircle the earth.

Any foreign material that mixes with and contaminates the air in the atmosphere.

1. Electromagnetic radiation, caused by natural electrical disturbances in the atmosphere, which interferes with radio systems; also known as atmospherics or strays.
2. The radio frequency electromagnetic radiation originating, principally, in the irregular surges of charge in thunderstorm lightning discharges.

Atmospherics are heard as a quasi-steady background of crackling noise (static) on certain radio frequencies; such as, those used to broadcast AM radio signals.

Since any acceleration of electric charge leads to emission of electromagnetic radiation, and since the several processes involved in propagation of lightning lead to very large charge accelerations, the lightning channel acts like a huge transmitter, sending out radiation with frequencies of the order of 10 kHz.

1. An atmospheric condition in which the air temperature rises with increasing altitude, holding surface air down and preventing dispersion of pollutants.
2. A departure from the usual increase or decrease of an atmospheric property with altitude.

It usually refers to an increase in temperature with increasing altitude, which is a departure from the usual decrease of temperature with height.

3. A reversal in the normal temperature lapse rate, the temperature rising with increased elevation instead of falling.

Usually, within the lower atmosphere (the troposphere) the air near the surface of the earth is warmer than the air above it, largely because the atmosphere is heated from below as solar radiation warms the earth's surface, which in turn then warms the layer of the atmosphere directly above it.

1. The process by which neutral atmospheric molecules or atoms are rendered electrically charged chiefly by collisions with high-energy particles.
2. The charging of neutral particles in the atmosphere through violent contact with charged particles.
3. The production of ions in the atmosphere by the loss of an electron from a molecule, typically, for example, by cosmic rays or cosmic radiation.

Cosmic rays and radioactive decay are the main sources of atmospheric ionization.

Radioactivity at the surface can also produce ions in the lowest layer of the atmosphere.

1. The rate of decrease with height for an atmospheric variable.

The variable involved is temperature unless specified otherwise. The lapse rate is the rate of decrease with height and not simply the rate of change.

While most often applied to the earth's atmosphere, the concept can be extended to any gravitationally supported ball of gas.

2. The rate of decrease of temperature with elevation in the atmosphere.

The environmental lapse rate is determined by the distribution of temperature in the vertical at a given time and place and should be carefully distinguished from the process lapse rate, which applies to an individual air parcel.

1. Any one of a number of layers of the atmosphere, most commonly distinguished by temperature distribution.
2. One of several strata or layers of the earth's atmosphere.

Temperature distribution is the most common criterion used for denoting the various shells.

1. Noise heard during radio reception due to atmospheric interference.
2. Noise heard in a radio receiver because of interference from the atmosphere.

1. A branch of atmospheric physics or physical meteorology in which optical phenomena occurring in the atmosphere are described and explained.
2. The study of the optical characteristics of the atmosphere or products of atmospheric processes.

The term is usually confined to visible and near visible radiation; however, unlike meteorological optics, it routinely includes temporal and spatial resolutions beyond those discernible with the naked eye.

Meteorological optics is that part of atmospheric optics concerned with the study of patterns observable with the naked eye.

This restriction is often relaxed slightly to allow the use of simple aids; such as, binoculars or a polarizing filter.

Topics included in meteorological optics are sky color, mirages, rainbows, halos, glories, coronas, and shines.

A branch of science dealing with the investigation and study of the physical phenomena of the atmosphere.

In petroleum engineering, the preparation of petroleum specimens for testing purposes by aging them at normal atmospheric pressure for a given period of time at particular temperature and humidity.

1. A unit of pressure that is taken to be the standard pressure of the earth's atmosphere at sea level.
2. The pressure at any point in an atmosphere due solely to the weight of the atmospheric gases above the point concerned.
3. The average atmospheric pressure at sea level is approximately 14.7 pounds per square inch.

With an increasing altitude, the pressure decreases; for example, at 30,000 feet, approximately the height of Mt. Everest, the air pressure is 4.3 pounds per square inch.

In geophysics, the radiation emitted by the atmosphere either upward into space or downward toward the earth, consisting mainly of long-wavelength terrestrial radiation plus the small amount of short-wavelength solar radiation absorbed in the atmosphere.

A radio wave that is propagated by reflection through the atmosphere by reflections and refractions occurring in the atmosphere.

It may include either the ionospheric wave or the tropospheric wave, or both.

1. An instrument used for the detection or measurement of electromagnetic radiation.

The term is applied in particular to devices used to measure infrared radiation.

2. A receiver for detecting microwave thermal radiation and similar weak wide-band signals that resemble noise and are obscured by receiver noise.

The primary application of an atmospheric radiometer has been on board spacecraft measuring atmospheric and terrestrial radiation, and they are mostly used for meteorological or oceanographic remote-sensing.

Their secondary application is also meteorological, as zenith-pointing surface instruments that view the earth's atmosphere in a region above the stationary instrument.

By understanding the physical processes associated with energy emission at these wavelengths, scientists can calculate a variety of surface and atmospheric parameters from these measurements, including air temperature, sea surface temperature, salinity, soil moisture, sea ice, precipitation, the total amount of water vapor and the total amount of liquid water in the atmospheric column directly above or below the instrument.

1. The refraction of light passing through the earth's atmosphere, including both astronomical refraction and terrestrial refraction.
2. An apparent upward displacement of celestial objects relative to the horizon as light from them is bent toward the vertical by the decreasing density with altitude of the earth's atmosphere.

It is greatest for objects on the horizon and negligible at elevations higher than about 45 degrees.

3. The angular difference between the apparent zenith distance of a celestial body and its true zenith distance, produced by refraction effects as the light from the body penetrates the atmosphere.

Any refraction caused by the atmosphere's normal decrease in density with height.

Near surfaces on the earth, those within a few meters or so, are usually dominated by temperature gradients.

A diffusion or alteration in the direction of the propagation, frequency, or polarization of electromagnetic radiation through contact with, or by interaction with, the atoms in the atmosphere.

The twinkling of stars (fluctuation of intensity) as seen through a planet's atmosphere.

Scintillation is caused when the star's light is distorted by the Earth's atmosphere. Scintillation is greater for bright stars that are low on the horizon.

The measuring of atmospheric conditions above the effective range of surface weather observations.

The steam curing of concrete or cement products at atmospheric pressure; usually, at a maximum ambient temperature between 100 and 200°F or 40 and 95°C.

The constituting elements that characterize the atmosphere, including wind direction and velocity, altitude, air density, and the velocity of sound.

Any particles; such as, dust that are finely divided and suspended in the atmosphere.

1. A movement of atmospheric masses caused by the gravitational attraction of the sun and moon and by daily solar heating; amplitudes are minute except in the upper atmosphere.
2. The rhythmic, periodic oscillation of the earth's atmosphere because of the gravitational effects of the earth, sun, and moon and to the absorption of radiation by the atmosphere.
3. A tidal movement of the atmosphere resembling an ocean tide but caused principally by diurnal temperature changes.

Both the sun and moon produce atmospheric tides, and there also exist both gravitational tides (gravitational attraction of the sun or moon) and thermal tides (differential heating of the atmosphere by the sun).

Haziness in the atmosphere due to aerosols; such as, dust.

If turbidity is zero, the sky has no dust, as measured by a sun photometer; which is an instrument that measures luminous intensity or brightness, luminous flux, light distribution, color, etc.; usually by comparing the light emitted by two sources, one source having certain specified standard characteristics.

Random fluctuations of the atmosphere often causing major deformations of its fluid flow.

The mixing of warm and cold air in the atmosphere by wind, which causes clear-air turbulence experienced during airplane flight; as well as, poor astronomical vision or the blurring of images seen through the atmosphere.

1. A range of wavelengths in which the atmosphere is partly or largely transparent.
2. A wavelength band in the electromagnetic spectrum that is able to pass through the earth's atmosphere with relatively little attenuation through absorption, scattering, or reflection.