Chapter 22The Atmosphere

• Permanent: • Nitrogen-78%• Oxygen-21%, • Others - 1%

• Variable: • Water vapor (H2O) • Carbon dioxide (CO2) • Ozone (O3)• Particulates

Composition of the Atmosphere

Composition of the Atmosphere

• 99% permanent gases and 1% variable (trace) gases. – Permanent gases - constant concentration with

time & space.– Variable gases - varying concentration

depending upon where/when you are.

• All weather and climate are associated the 1% variable gases.

Parts of Atmosphere important to weather

1. Water Vapor- more in warmer locations- forms clouds and drives weather- absorbs heat to keep earth warm

Water Vapor Imagery

2. Carbon Dioxide• Absorbs energy

from the earth

3. Ozone– Ozone high in the atmosphere is good – Absorbs harmful UV rays– Ozone here is formed naturally

- Ozone low in the atmosphere is bad- creates smog- made by humans

4. Particulates- Volcanic dust, ash from fires, pollen- Absorb water and helps to form clouds- Absorbs/reflects sunlight

Atmospheric Pressure

• The weight of the air above a point

• Decreases with altitude

• Also changes with temperature and amount of water vapor in the air

• Measured with a barometer

• Standard Atmospheric Pressure = 1 atm or 760 mm of mercury or 1000mb

Atmospheric pressure variation

with altitude

Measuring Pressure

Mercurial Barometer-Tube filled with mercury-air pressure pushes on mercury from bottom-causes mercury to rise and fall

Aneroid Barometer- Metal expands and

contracts with changes in pressure

- Causes pointer to move so pressure can be read

Barograph- Recording aneroid

barometer- Keeps track of pressure

over several days

Layers of the Atmosphere

Troposphere

• Weather Sphere• Bottom Layer• Temperature decreases with height• Most clouds• Most water vapor• Most airplanes fly here

Stratosphere

• Ozone Layer• Increase Temp with height because ozone absorbs

UV

Mesosphere

• Temperature decreases to coldest point at the mesopause (-90⁰C)

• Many meteors burn up in this layer.

Thermosphere• Air is very thin. • Temperature increases due to absorption of solar

energy by nitrogen and oxygen• Satellites orbit here

Ionosphere – part of the thermosphere• Electrically charged layer• AM radio waves reflect off of here• Causes auroras

Create your OWN mnemonic phrase to memorize the order of the five layers. For example:

T = Troposphere = TerriblyS = Strostosphere = ScaryM = Mesosphere = MonstersT = Thermosphere = TerrorizeE = Exosphere = Earth