earths atmosphere composition earth science / mr. bimber
TRANSCRIPT
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