1. All About Air

2. Air: an invisible gaseous substance Basically, a bunch of gas particles floating around that we can’t see! Even though we can’t see the air, we can feel it! Air particles are all around us, filling up the “empty” space

3. Air pressure: The measure of the force with which air molecules push on a surface These air molecules are all around us, pushing on everything and everybody That push creates pressure!

5. Were you listening? Let’s find out! Can you answer these questions? How much pressure is exerted (put out) on every surface of your body? Do you feel it? Why? 14.7 pounds per square inch No We do not feel it because the pressure is spread out around our whole body. The air is pushing from every direction.

6. Atmosphere: the mixture of gasses that surrounds a planet or a moon The air particles are attracted to the Earth’s gravity – that’s why they hang around here! Earth’s atmosphere has 5 different layers Earth’s atmosphere is composed (made up of) many different gasses What gas do you think makes up most of Earth’s atmosphere?

7. Nitrogen = 78% - The most common atmospheric gas. -It is released when dead plants and animals break down and when volcanoes erupt. Oxygen = 21% - The second most common atmospheric gas. - It is made by phytoplankton and land plants. *Mixture = 1% -Made up of Argon, Carbon dioxide, water vapor, and other gases

9. Were you listening this time? Let’s find out! Can you answer these questions? What is the most abundant gas in our atmosphere? What is the second most abundant? Is the air only made up of gasses? Nitrogen 78% Oxygen 21% No, it also has solids in it. Things like industrial smoke, dust, volcanic ash, and meteor dust.

10. Earth’s atmosphere has 5 layers Troposphere -Closest to Earth Stratosphere Mesosphere Thermosphere Exosphere -Farthest away