Small particles of dust released into the atmosphere by many natural processes and human activities.

The second layer of the atmosphere, above the troposphere, containing the ozone layer that absorbs and scatters ultraviolet solar radiation.

The layer of gases surrounding Earth, composed primarily of nitrogen and oxygen, which regulates climate and weather.

The outermost layer of Earth's atmosphere, where the atmosphere thins out and merges with outer space.

The third layer of Earth's atmosphere, located above the stratosphere and below the thermosphere, where temperatures decrease with altitude.

The fourth layer of Earth's atmosphere, located above the mesosphere and below the exosphere, characterized by high temperatures due to absorption of solar radiation.

The lowest layer of Earth's atmosphere, where most weather occurs and where nearly all life exists. It is closest to Earth's surface and contains the air we breathe.

The movement of heat by the physical movement of a fluid (liquid or gas) due to differences in temperature and density.

The transfer of energy through space by electromagnetic waves, such as the sunlight reaching Earth. It includes radiant energy, which is given off by objects.

The process by which heat energy is transmitted through collisions between neighboring atoms or molecules.

A layer in the stratosphere (at approximately 20 miles) that contains a concentration of ozone sufficient to block most ultraviolet radiation from the sun.