Chapter 1

The Atmosphere

Section 1

The Air Around You

Importance of the Atmosphere

• The weather is the condition of Earth’s atmosphere at a particular time and place.

• Earth’s atmosphere is the layer of gases that surrounds the planet.

• The atmosphere is constantly changing, with atoms and molecules of gases moving around the globe and in and out of living things, the land, and the water.

Importance of the Atmosphere

• Living things need warmth and liquid water. The atmosphere can trap the energy from the sun to keep Earth’s surface warm enough for water to stay a liquid.

• Earth’s atmosphere also protects us from harmful sun radiation and from comets and meteors.

Importance of the Atmosphere

• Earth’s atmosphere is made up of nitrogen, oxygen, carbon dioxide, water vapor, and many other gases, as well as particles of liquids and solids.

Composition of the Atmosphere

Composition of the Atmosphere

• Nitrogen (N2)– The most abundant gas in the atmosphere (78%)– Essential to all living things.– We get our nitrogen requirements from eating

protein.

Composition of the Atmosphere• Oxygen (O2)– The second most abundant gas (21%)– Essential to living things– We are able to take oxygen directly from the air– Oxygen is also involved the process of burning

(without oxygen, a flame would go out) and rusting

– Ozone (O3) is a form of oxygen that has 3 atoms instead of the usual 2.

• Carbon Dioxide (CO2)– Makes up less than 1% of the atmosphere– Essential to life because plants need it to

survive (and we need plants to survive)– Animals (including humans) give off CO2 as

a waste product

Composition of the Atmosphere

Composition of the Atmosphere

– When coal and gasoline are burned, they release CO2 and increase the amount in the atmosphere

– This is slowly increasing the Earth’s temperature in a process called global warming

• Other Gases– Nitrogen and oxygen make up 99% of the atmosphere– Argon and carbon dioxide makes up most of the

remaining 1%– The remaining gases are called trace gases because only

small amounts of them are present

Composition of the Atmosphere

• Water Vapor (H2O)– The amount of water vapor

in the air varies from place to place and from time to time (example: North Pole has very little, Costa Rica has up to 4%)

– Clouds form from water vapor and eventually cause our precipitation, an important part of the water cycle

Composition of the Atmosphere

• Particles– Pure air contains only gases, but

that only exists in laboratories– In reality, air is filled with tiny

solid and liquid particles of dust, smoke, salt, and other chemicals

– They are usually too small to see, but if pollution is bad enough then we can see them in the air

Composition of the Atmosphere