Oxygen makes up about _____ of the total gases on Earth.

The layers of the atmosphere are classified according to the changes in

The air tempature is most likely lowest at

Nitrogen represents about ______ of Earth's atmosphere.

In the troposphere as the altitude increases the temperature _____

The layer closest to the Earth

Air pressure is greater at

The layer containing the ozone layer

The warmest layer

contains the ionosphere

Altitude is greater at

The coldest layer

Where the space shuttle orbits

Shield's you from the Sun's harmful energy by absorbing most of the Sun's ultraviolet radiation.