1. Chapter 15.1 The air around you
Key Concepts: What is the composition of the earth’s atmosphere? How is the atmosphere important to living things?
Key terms: weather, atmosphere, ozone, water vapor

2. Weather
Weather is the condition of Earth’s atmosphere at a particular time and place.
The atmosphere is the envelope of gases that surrounds the planet.

3. Condition of the atmosphere
Earth’s atmosphere is made up of nitrogen, carbon dioxide, water vapor, and many other gases, as well as particles of liquids and solids
Nitrogen – most abundant gas in the atmosphere (about 75%)
Oxygen – 2nd most abundant, makes up less than 25%
Involved in a lot of processes (eg burning/combustion)
Ozone – 3 oxygen atoms together.

4. Atmosphere continued Carbon dioxide – 1 carbon to 2 oxygen.
Plants need it to produce food
Fuel burning releases it
Other gases – oxygen and nitrogen make up 99% of dry air
Water vapor – water in its gas form
Particles – pure air contains only gas. “Pure” air only exists in laboratories.

5. Importance of the atmosphere
Earth’s atmosphere makes conditions on Earth suitable for living things.
Contains oxygen and other gases that living things need to survive.
Warmth and liquid water
Atmosphere protects Earth’s surface from being hit by asteroids.