Our planet is surrounded by an invisible shell of air, called the atmosphere, held in place by the Earth’s gravitational field. It’s made up of a mixture of different gases. About 78% of the ...

Many human activities release polluting gases into the atmosphere, such as farming animals ... These layers each have different structures and properties. Rock types There are three types of ...

Some parts of Earth's atmosphere are studied continuously in ... Look a little higher, however, and the story is completely different. The mesosphere, the layer of sparse air above the ...