air atmosphere

mesopause

the boundary in the earth's atmosphere between the mesosphere and the thermosphere, at which the temperature stops decreasing with increasing height and begins to increase.

meteorology

the branch of science concerned with the processes and phenomena of the atmosphere, especially as a means of forecasting the weather.

atmosphere

the envelope of gases surrounding the earth or another planet.

air

the invisible gaseous substance surrounding the earth, a mixture mainly of oxygen and nitrogen.

ionosphere

the layer of the earth's atmosphere that contains a high concentration of ions and free electrons and is able to reflect radio waves. It lies above the mesosphere and extends from about 50 to 600 miles (80 to 1,000 km) above the earth's surface.

mesosphere

the region of the earth's atmosphere above the stratosphere and below the thermosphere, between about 30 and 50 miles (50 and 80 km) in altitude.

biospher

the regions of the surface, atmosphere, and hydrosphere of the earth (or analogous parts of other planets) occupied by living organisms.

lithosphere

the rigid outer part of the earth, consisting of the crust and upper mantle.

climate

the weather conditions prevailing in an area in general or over a long period.

aurora australis

Its southern counterpart, the aurora australis (or the southern lights), has features that are almost identical to the aurora borealis and changes simultaneously with changes in the northern auroral zone. It is visible from high southern latitudes in Antarctica, Chile, Argentina, New Zealand, and Australia.

aurora borealis

The Aurora Borealis (Northern Lights) and Aurora Australis (Southern Lights) are the results of electrons colliding with the upper reaches of Earth's atmosphere. (Protons cause faint and diffuse aurora, usually not easily visible to the human eye.)

homosphere

The definition of homosphere is the lower area of Earth's atmosphere. The 43-mile deep layer of the earth's atmosphere that you live in is an example of the homosphere.

heterosphere

The heterosphere is the upper portion of the Earth's atmosphere, in which gases are fractionated according to their molecular weight. It lies above the homosphere, where chemical constituents are well mixed. On average the heterosphere begins at an altitude of about 80 km

aerosols

a substance enclosed under pressure and able to be released as a fine spray, typically by means of a propellant gas.

hypothesis

a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.

hydrosphere

all the waters on the earth's surface, such as lakes and seas, and sometimes including water over the earth's surface, such as clouds.