The Atmosphere, Global Circulation, and Climate Topic 6

The Atmosphere Atmosphere pie Layers of air above us, separated by thermoclines Troposphere –78% N 2 –21% O 2 –1% Gases, water vapor, dust, soot particulates –Involved in biogeochemical cycling Stratosphere –Similar concentrations of gases with two exceptions: H 2 O is much lower and O 3 is much higher –ozone layer= “global sunscreen” –produced when O 2 interacts with UV light Figure 19.2

The Earth Greenhouse Naturally occurring CO 2, H 2 O, N 2 O, and CH 4 help to keep the earth warm. This supports life. Historically, CO 2 has been 300 ppm, now it is 400 ppm © NPS

Local climates are affected by –uneven heating of the earth’s surface by solar energy –seasonal changes in temperature and precipitation –rotation of earth on axis –properties of air, land, and water

Properties of air Density Water vapor holding capacity Response to pressure changes Latent heat release SO, in the atmosphere there is lots of heat transfer going on. What is the fancy name for this? CONVECTION!

Convection Currents

ATMOSPHERIC PATTERNS OF AIR MOVEMENT

Reality: factor in the Coriolis EffectCoriolis Effect Earth is spinning faster at the equator than the poles.

Coriolis Effect This causes a deflection of things traveling straight north or straight south.

Coriolis Effect In the northern hemisphere, deflection is to the right of the wind direction. In the southern hemisphere, deflection is to the left of the wind direction.

Prevailing wind patterns= convection cells+Coriolis effect

Ocean surface currents

Deeper water currents (thermohaline circulation)

Local climate is determined by… Distribution of heat by air and ocean currents Distribution of precipitation by air currents Seasonal changes in solar radiation distribution (which in turn affects the two properties above)

Seasons

Earth’s Current Climate Zones Figure 5-2

Topography and Local Climate: Land Matters Interactions between land and oceans and disruptions of airflows by mountains and cities affect local climates. Miller 15th edition Figure 5-8

© McGraw-Hill “Normal” Circulation in the Pacific Ocean

© McGraw-Hill El Niño-Southern Oscillation (ENSO)