Earth’s Atmosphere

Composition

Earth Science / Mr. Bimber

What’s in the air?

The atmosphere is:• 78% nitrogen• 21% oxygen• 1% argon• 0.04% carbon dioxide• Varying amounts of:

– water vapor – pollutants– dust

What are the different layers?

• Outer Space• (Exosphere)• Thermosphere • Mesosphere• Stratosphere • Troposphere• Solid earth

Troposphere

• Has most of the air• Higher it’s cooler• Most clouds are here• Storms happen here• 9-16 kilometers high• Bottom layer

Stratosphere

• Second lowest layer• 10-50 kilometers high• Has cool, dry air• Above the clouds• Higher its warmer• Ozone layer heats it• Some planes fly here

Mesosphere

• “meso” means middle• 50-90 kilometers high• Higher it’s cooler again• Top is -110 Fahrenheit

Thermosphere

• Above Mesosphere • About 100 kilometers• Friction with solar wind

causes “northern lights”• Higher it’s warmer again• “thermo” means hot• Top is 1,800 Fahrenheit

Exosphere

• Top layer• Above 100 kilometers• Fades out to nothing

How was our atmosphere formed?

• Comets and meteors• Earth melted inside• Volcanoes erupted

– Gases– Steam

• Rivers, lakes, oceans

• Plants – Released oxygen

• First animals• Life possible on land

Is our atmosphere changing?• Big meteors

– Fires, tidal wave– Dust

• Block sunlight– Cools the planet– Extinction

» Dinosaurs» Us?

• Industry (humans)– CFCs

• Ozone hole– Acid rain– Smog– Carbon dioxide

• climate change

Why are there layers?

Temperature changes:

Outer Space• Cooling• Heating• Cooling• Heating• Cooling

Solid Earth

How does heat move?

• Conduction– Atoms bump each

other.

• Convection– Hot atoms expand and

flow upward

• Radiation– Waves travel through

space

Conduction

• Heat = energy of atoms vibrating.

• When fast moving atoms speed up their slow neighbors, that’s conduction.

• Mostly solids, liquids• Metals conduct heat

faster than wood.

Convection

• Hot gases and liquids expand and float up.

• Cold gases and liquids shrink, and sink.

• Heat travel by flowing atoms is called convection.

• “Heat rises” - that’s why flames point upward.

Radiation

• Heat can travel in waves, like light.

• This is called radiation.• Radiation from the sun is

called insolation (short for INcoming SOLar radiATION )

• Earth radiates some heat out to space.

Heat flows through the atmosphere

• Temperature changes differently in each layer.

• The air is heated:– At ground level– In the Ozone layer– By friction with solar wind

Heat in the Atmosphere

• The balance and flow of heat energy in the atmosphere– Causes weather– Protects life on earth