The Atmosphere

You live at the bottom of an ocean of air. That ocean of air is called the atmosphere, and it wraps all the way around our planet. The air in the atmosphere is pulled down by gravity, so it has weight. All that air pressing down on you is called air pressure. The push of the air is surprisingly strong, but you do not feel it because the air inside your body pushes back just as hard.

The atmosphere is made of layers. The layer closest to the ground is called the troposphere, and it is where all weather happens. Clouds, rain, wind, and storms all form in this lowest layer. Higher up are more layers, including the stratosphere, where a special gas called ozone blocks harmful rays from the Sun.

The atmosphere also works like a cozy blanket. It traps some of the Sun's warmth so Earth stays warm enough for living things. Without it, our planet would be freezing at night and scorching in the day, and life as we know it could not survive.

The atmosphere is like a shield and a blanket wrapped around Earth. It forms a protective boundary between outer space and all the living things on the surface.

The atmosphere is made of layers stacked on top of each other. The lowest layer is the troposphere, and that is where we live and where weather happens. Above it sit the stratosphere, the mesosphere, and the thermosphere, each one higher than the last.

The atmosphere also helps control Earth's temperature. Some gases in the air act like the glass of a greenhouse. They let sunlight in and hold on to some of its heat. This is called the greenhouse effect. A little greenhouse effect is a good thing, because it keeps Earth warm enough for life. Too much of it can cause problems, which is why scientists watch it carefully.

Ozone is a gas made of three oxygen atoms joined together. It is found in two layers of the atmosphere, and it behaves very differently in each one.

High above the ground, in the stratosphere, ozone is helpful. This good ozone forms a layer that blocks harmful ultraviolet rays from the Sun. Those rays can hurt skin, eyes, and plants, so the ozone layer acts like sunscreen for the whole planet.

Close to the ground, in the troposphere where we live and breathe, ozone is harmful. This bad ozone is an air pollutant. It is a main ingredient of smog, the dirty haze that hangs over some cities. Breathing it can hurt our lungs, and it also damages crops, trees, and other plants.

Protecting the ozone layer above us, while keeping the air below clean, helps keep people and nature healthy.

Earth's atmosphere has not always been the way it is today. Long ago, before there were plants, the air had very little oxygen. Tiny living things changed that. Over millions of years, they released oxygen into the air, which made it possible for animals, including us, to breathe.

The atmosphere also keeps our planet warm through the greenhouse effect. Certain gases trap some of the Sun's heat, like a blanket holding in warmth. Without this natural warming, Earth would be too cold for most life.

Today, people are adding extra heat-trapping gases to the air by burning fuels like coal, oil, and gas. This makes the blanket thicker, so Earth is slowly getting warmer. Scientists call this global warming, and it is changing climates around the world. Learning how the atmosphere works helps us take better care of the only home we have.

Earth is wrapped in a mixture of gases called the atmosphere. Most of the air is nitrogen, about 78 parts out of every 100. Oxygen makes up about 21 parts, and that is the gas we need to breathe. The last little bit, about 1 part in 100, is a mix of water vapor, argon, carbon dioxide, and tiny amounts of other gases.

The atmosphere is not one single layer. It has five main layers, stacked up by height. Scientists tell the layers apart by how the temperature changes as you go higher. In some layers the air gets warmer as you climb, and in others it gets colder.

The troposphere is the layer closest to the ground, and it is where all our weather happens. Rain, snow, wind, and clouds are all troposphere events. The next layer up is the stratosphere, home of the ozone layer that protects us from the Sun's harmful rays.