People can (and do) write books and PhD theses on this- the point being the are many fascinating aspects and impacts of atmospheric science. To answer your question in a reasonable amount of space- I will try to hit the main points.

1. Warmth- The atmosphere is crucial to trapping heat from the sun. This is the same effect that is currently causing issue with global warming due to increased greenhouse gases. However, this just emphasizes the point that we need a crucial balance- no atmosphere and our planet would freeze, too much and it will be too hot. Mercury is a great example of the first scenario. It is the closest planet to the sun, but has no atmosphere. When the surface of Mercury faces the sun, temperatures can reach as much as 800 degrees F, but when the surface is not facing the sun (so at night) the temperature can drop to negative 290 degrees F. The lack of atmosphere means it cannot retain any heat. For the scenario of too much atmosphere, look at Venus- it has a dense CO₂ atmosphere, and surface temperatures range between 467 and 872 degrees F- so it is able to maintain a large amount of heat!

2. Giving us oxygen to breath (and C0₂ for plants)- Our atmosphere is about 78% nitrogen, 21% oxygen, and 1% other (mostly argon with trace a mounts of CO₂ and other gases). We need oxygen to breath, so that 21% is hugely important for us, but we also heavily rely on plants for food and to produce said oxygen, and the trace amounts of C0₂ are important for them.

3. Protecting us from the sun- This is a point I feel many do not realize, but our atmosphere is one of the largest barriers protecting us from harmful rays from the sun. To put this in perspective, the atmosphere has a larger impact on blocking solar radiation than the shell of an airplane! As you go higher in the atmosphere, it becomes thinner, thus it is not able to block as much radiation. This is actually an issue for airline pilots/flight attendants who spend lots of time in the air. The shell of the airplane does not compensate for this loss in atmospheric protection, and they need to be careful to not exceed how much time they spend flying at high altitudes in order to not receive too many damaging rays from the sun.

Great question! Where to begin. First, the atmosphere shields us from the Sun's dangerous radiation. Certain UV rays are blocked from reaching us. Second it traps heat to make Earth comfortable to live on. Otherwise we might be as cold as Mars or warm as Venus. That is a whopping 800+ degrees F. Third, it holds the proper mixture of gases that we need to breathe. For instance nitrogen and oxygen! Fourth, the water cycle makes life possible on Earth. On a rainy day you look outside and see the water cycle at work. Those rain clouds form in the atmosphere. You understand why the atmosphere is important!

The atmosphere is important for many reasons. It gives us air to breathe and for birds to fly in. It protects us from dangerous solar radiation. It is where precipitation forms. It maintains our climate. Almost anything you can think of relies on the atmosphere in some way.

1. The atmosphere is what we breathe.
2. The atmosphere protects us from the vacuum of space.
3. The atmosphere is the blanket that protects from freezing at night, when the sun isn't shining.
4. The atmosphere has the carbon dioxide that plants use to make to make the sugars that we and other life on earth need for food.

Too many reasons to list.

The atmosphere contains all our weather, prevents our oceans from boiling off, contains gasses that we need to survive, causes a greenhouse effect that prevents Earth from freezing, stops particularly harmful cosmic radiation, is needed for any number of chemical processes... the list goes on.

The atmosphere is very important for life on Earth. The atmosphere has different layers, and the bottom layer has oxygen in it which we, plants and animals need to survive.

The other very important thing about the atmosphere is that is shields us from the sun. The sun has extremely hot rays that warm our planet. We need the heat of the sunshine, and the light, for plants to grow. But let's imagine that there was no atmosphere -- the sun rays would be too hot, and too strong for life to survive. Everything would be sunburnt!

One more thing the atmosphere does for us, is it creates weather patterns. When we get clear skies, snow or rain, this is because of currents in the atmosphere.