Climate Change 1020 Lecture Oct 16, 2006 Lis Cohen

Today’s Lecture Weather –What makes weather? Is energy from the sun evenly distributed? –Sun heating the earth –Deficits and Excess How does this energy move to create less of a gradient (difference over space)? –One cell vs. Three cell model –Pressure Gradient Force, Coriolis, Friction What moves the energy? –Mid latitude storms

What makes weather? Unequal heating of the Earth!!! –This unequal energy is moved and distributed to other places on Earth.

Although, Energy in = Energy out, the distribution of energy with latitude is uneven.

Tropics have a surplus of energy and the poles a deficit. A net poleward transport of energy is therefore required. ENERGY

Our atmosphere is a three cell model. These three cells transport energy to the poles.

Other planets show evidence of multiple cell atmospheres…

How does the energy (heat) move from equator to the poles? Vertical winds and horizontal winds transport the energy!

Winds Patterns Balance of 3 forces 1.The pressure gradient force causes wind to blow from high pressure toward low pressure. 2.The coriolis force causes wind to be deflected to the right of the motion in the northern hemisphere. 3.Friction which slows the wind.

Pressure Gradient Force

If the earth was not spinning, air would move directly from high to low pressure areas.

Winds Patterns are a balance of 3 forces 1.The pressure gradient force causes wind to blow from high pressure toward low pressure. 2.The coriolis force causes wind to be deflected to the right of the motion in the northern hemisphere. 3.Friction which slows the wind.

Coriolis Effect

Coriolis Videos Video 1 of the Coriolis Effect

Coriolis (Northern Hemisphere- air moves to the right of the initial motion) Direction of initial motion

Coriolis (Northern Hemisphere- air moves to the right of the initial motion) Highs – clockwise rotation Lows – counterclockwise rotation (cyclonic) Northern Hemisphere Surface map Northern Hemisphere Satellite map Northern Hemisphere Wind map

Coriolis (Southern Hemisphere - Air moves to the left of the initial motion) Direction of initial motion

Coriolis (Southern Hemisphere - Air moves to the left of the initial motion) Highs- counterclockwise rotation Lows- clockwise rotation Southern Hemisphere Satellite Southern Hemisphere Winds Southern Hemisphere Pressure

Coriolis (earth turns underneath the slower wind) Direction of initial motion

Coriolis Effect

Winds Patterns are a balance of 3 forces 1.The pressure gradient force causes wind to blow from high pressure toward low pressure. 2.The coriolis force causes wind to be deflected to the right of the motion in the northern hemisphere. 3.Friction which slows the wind.

Pressure Gradient and Coriolis L H Initial Motion

Pressure Gradient and Coriolis and Friction L H Initial Motion

Pressure Gradient and Coriolis and Friction L H New Motion

The poleward transport of energy occurs in the fronts and low pressure systems of the middle latitudes.

Warm Fronts COLD AIR Transport warm air and water vapor (energetic water) from the equator, to the poles.

Warm Fronts COLDER AIR WARM AIR

Cold Fronts COLD AIR WARM AIR Cold fronts usually transport colder and drier air (less energetic air) towards the equator.

Water Vapor Transport Pathway

Energy Emitted by the Earth Most is absorbed by atmosphere IR satellites use this window to see the temperature of the cloud tops. Atmospheric Window: Important to the energy balance of the planet. A body at 288 K (Earth) temperature emits most of its energy in this wavelength region.

Meteo 1020 Lecture 3 Weather and Climate Satellite images in this band are from reflected sunlight Atmospheric Window - Wavelength region of infrared satellite images- responds to the temperature of the cloud tops. The atmospheric window is also important to the energy balance of the planet. A body at 288 K temperature (the earth’s average surface temperature) emits most of its energy in this wavelength region. This figure shows the transparency of various wavelength bands important to absorption of energy in the earth’s atmosphere