Composition & Structure ATMOSPHERE Composition & Structure

Why do we have seasons?

What are the major gases in the Earth’s atmosphere? Nitrogen: 78% Oxygen (O2): 21% Argon: 0.93% Trace gases, include carbon dioxide, water vapor, methane, nitrous oxide, ozone, CFCs

Atmospheric gases Some are permanent Some are variable i.e.: stable concentrations Include neon, helium, others Some are variable Include water vapor, CO2

Goldilocks principle Venus, Mars: similar gases, but very different: Venus has thick atmosphere; Mars, almost no atmosphere. Earth has pressure intermediate

Review What are the major gases in the atmosphere? Why is Venus so warm and why is the Earth as warm as it is?

Layers of the atmosphere Most important: Troposphere Stratosphere

Layers of the atmosphere Ozone maximum is the stratospheric ozone = good ozone Ozone in troposphere = bad ozone

Troposphere Our sphere Weather Notice: patterns Temperature Winds Layer ends when temp. no longer varies with height = tropopause

Review What are the layers of the atmosphere? What is ozone and where is it found? Distinguish “good” and “bad” ozone.

Water cycle Connects ocean and atmosphere Key pt: what happens in the atmosphere depends a lot on what happens in the ocean

What happens to solar radiation Energy from sun Some absorbed by gases (O3, H2O) Some reflected by clouds and by the Earth’s surface Last is called albedo

albedo Notice snow, water, and clouds What feedback effects would you expect from melting of ice caps?

Albedo Go to NEO--NASA Earth Observations

Energy transfer

Energy transfer Simplified earth: slow rotation to east, no interaction of oceans and land Sun warms equator, air rises, spreads north and south Cold air at poles sinks and replaces Air deflected by rotation, to right in N hemisphere, to left in S hemisphere Coriolis effect Rain at the equator, as the rising air cools and loses moisture Air descends at 30 degrees N and S Result??