Circulation in the atmosphere

What regulates the motion of fluid particles in the ocean and atmosphere? Newton’s Law

Differential Heating From Equators to Poles

What drives the circulation of the atmosphere? Heating by the sun  AIR PRESSURE Equator/Tropics Higher Latitudes surface troposphere

Vertical view of air pressure (global convection) High Pressure Low Pressure Low Pressure

+ _ Horizontal view of air pressure at ocean surface High Pressure Higher Latitudes Surfaces of constant pressure y (latitude) x (longitude) _ Equator/Tropics Low Pressure

Newton’s Law Motion across Latitudes Motion along Latitude v y (latitude) x (longitude) u Motion across Latitudes Motion along Latitude

Non rotating view of Atmospheric Circulation

Hurricane IVAN H H L H H

North Hemisphere Fpressure FCoriolis Low Pressure High Pressure Rate of Rotation North Hemisphere Low Pressure B t1 t2 t3 t4 t5 A Fpressure High Pressure FCoriolis

North Hemisphere Fpressure FCoriolis High Pressure Low Pressure Rate of Rotation North Hemisphere A B High Pressure Low Pressure t1 t2 t3 t4 t5 Fpressure FCoriolis

Fpressure FCoriolis Fpressure FCoriolis Fpressure Fpressure FCoriolis When this balance is reached the movement of the particles (and therefore of the flow) is called geostrophic motion

Newton’s Law Motion across Latitudes Motion along Latitude v y (latitude) x (longitude) u Motion across Latitudes Motion along Latitude

Some practical rules to remember: Fpressure Low Pressure High Pressure FCoriolis Particle will have the Coriolis force 90 degrees to the right Particles will tend to move along line of constant pressure Particles will have the high pressure on their right (same as Coriolis)

Hurricane IVAN H H L Fpressure H H FCoriolis

L H Vortices Low Pressure System High Pressure System Fpressure FCoriolis FCoriolis Fpressure Low Pressure System High Pressure System

Non rotating view of Atmospheric Circulation High Pressure Low Pressure

Redistribution of Heat – Large scale convective Cells Schematic depiction of the development of the atmospheric circulation, starting from a state of rest Easterlies (Trades) Westerlies Redistribution of Heat – Large scale convective Cells

Easterlies (Trades) Westerlies Schematic depiction of the development of the atmospheric circulation, starting from a state of rest Easterlies (Trades) Westerlies

Vertical view of the atmosphere Pole Equator

L L H H H L L L H H H L L Polar High Subpolar Low Subtropical High Eq. Low L L H H H L L

Vertical view of the atmosphere and Poleward Transport of Heat Equator

Midlatitude Cyclones

Poleward Heat Transport

The seasonal cycle

Differential Heating From Equators to Poles

Next time we will see how the ocean responds to the atmospheric wind and how it contributes to the heat transport