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

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.

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.

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.

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.