1. Composition of the atmosphere

2. We have a MYSTERY guest with us today.
What does air look like?
-With your group, draw what air looks like on your paper.
-You cannot use words, only pictures!

3. Composition of the Atmosphere
Composition = what something is made of.
“Air” is all around us and it behaves often like a liquid- it flows, moves, and causes things to happen (weather!)
Air = mixture of dozens of types of gases.

4. Air has MASS!! This means it can exert a FORCE (push) on you!
The air that surrounds the planet is held in place by gravity and is
called our atmosphere.
Gravity becomes less and less
as you move away from Earth.
As a result, there are fewer and
fewer molecules as you move
away from the surface.

5. Air!!! The air around us is 78%: NITROGEN 21% of the air around us is:
OXYGEN
The remaining 1% is a mixture of all other gases:
Carbon dioxide, helium, argon, neon, hydrogen…

7. Water Vapor
Water is present in gas form in the air we breathe. We call this water vapor.
The amount of water vapor in the air is called “humidity” and varies greatly with time and location.
Water vapor is an important part of the water cycle and is a driving force in most types of weather.

8. POP QUIZ 1. ________ is a mixture of gases.
2. ________ is a blanket of gases that surrounds a planet.
3. 78% of our atmosphere on Earth is made of what gas?
4. 21% of our atmosphere on Earth is made of what gas?
5. Humidity refers to the amount of water __________ in the air.