Atmosphere

A layer of air that forms a protective covering

around the planet.

Our atmosphere serves two purposes:

1. Protects life on Earth from the Sun’s harmful rays.

2. Maintains a balance between amounts of heat absorbed from the sun and the amount of heat that escapes back into space.

Composition of the atmosphere:

The atmosphere is composed of:

• Solids- dust, pollen, salt

• Liquids- water etc.

• Gases-

• Nitrogen (78%) produced from– volcanic eruptions,– dead and decaying plants.

• Oxygen (21%)– produced by plants (photosynthesis)

Atmosphere is composed of 5 layers. These layers are based on pressure and temperature, which are affected by altitude.

Atmosphere

Air Pressure Temperature

-as altitude increases, - as altitude increases

air pressure decreases temperature changes Which are effected by

Altitude

As altitude increases, air pressure decreases.

As altitude changes, so does the temperature.

Both air pressure and temperature are affected by the altitude

• As altitude increases, pressure decreases. The molecules at the bottom layer (Troposphere) have more pressure on them to force them together than those at the top layer (Thermosphere).

• Temperature differences result from the way solar energy is absorbed as it moves down through the layers of the atmosphere.

• Troposphere: 0 – 16 km

• Tropo=turning or changing

• Weather takes place here

• 90% of the atmosphere’s total mass

• -60°c at the top of the troposphere

• As altitude increases, temperature decreases

• Stratosphere: 16 – 50 km• Strato= layer or spreading

out• Jet stream = contains broad,

fast flowing “rivers of air” called jet streams. These jet streams can change weather patterns in the troposphere.

• Upper layer is warmer than lower due to ozone layer.

• Ozone layer= O3 (Ozone) absorbs sun’s ultraviolet rays, so temperature increases. IT is very thin, only 2.5-3.5 mm thick. O2 (Oxygen) vs O3 (Ozone).

• -60°c to 0°c

• Mesosphere: 50 – 80 km• Meso = middle• Temperature decreases

as altitude increases.• Outer mesosphere is the

coldest part of the atmosphere. -93°c at the top.

• Protects Earth’s surface. This is where meteoroids burn up upon entry into the atmosphere: “shooting stars”.

• Scientists have recently discovered large windstorms with winds speeds up to 320 km/h in this layer.

• Thermosphere: 80 – 550 km

• Thermo = heat• Largest layer, .001

percent as dense as the air at sea level.

• Temperature increases as altitude increases. Temperatures reach 1700°c.

• Very hot because energy coming from the sun strikes this layer first.

• Energy = heat

• Ionosphere:• Lower layer of the

thermosphere composed primarily of oxygen.

• Absorbs x-rays and gamma rays, which contribute to the high temperature and cause the gas molecules to become electronically charged (ions).

• Aurora Borealis/Australis: The northern and southern lights. Particles from the sun enter and strike oxygen and nitrogen particles, causing them to glow.

• The ionosphere can reflect many types of radio waves, allowing them to bounce around the world.

• Exosphere: Above 550 km

• No true end of atmosphere. Gas molecules simply break free of Earth’s gravity and disperse.

• Space shuttles, ISS (International Space Station) and satellites orbit the earth in this layer. This is how long distance calls, satellite TV, internet, cell phones, etc., reach you.

5 Layers Revisited

Learning Targets• In your science journal, copy the target and rate

your level of understanding on a scale of 1-5

5= exceed expectations, 4= understand it, but couldn’t teach it, 3=I get it, but not all of it, 2=There’s a lot I still need to learn, 1= What are we doing?!

• I can explain the purpose and general characteristics of the earth’s atmosphere.

Learning Targets (Cont’d)

• In your science journal, copy the target and rate your level of understanding on a scale of 1-5

5= exceed expectations, 4= understand it, but couldn’t teach it, 3=I get it, but not all of it, 2=There’s a lot I still need to learn, 1= What are we doing?!

• I can name all of the layers of the atmosphere and explain the significance of each layer.