Download Air and Ocean Circulation Introduction

Air and Ocean Circulation
Introduction:
• Different substances take different amounts of energy to heat up.
– 1 kg of water takes about 4X more energy to heat than 1 kg of air
• This property is called Heat Capacity.
• Substances with a high heat capacity (can hold a lot of heat energy) are
called Heat Sinks.
– Oceans and atmosphere are the most important
Prevailing Winds:
• Winds that affect large areas of the world and are relatively constant.
• Caused by a combination of heating from the Sun and the Earth’s rotation .
• Sun warms the Earth more near the equator than anywhere else (so it’s hotter
there).
• The hot air by the equator “rises” towards the Earth’s poles until about 30o
latitude (30th parallel) where it cools and “falls” again.
• When the warm air rises, it creates an area of low pressure under it, which
pushes the air up into the sky.
• Once the air is high enough, it spreads towards the Earth’s poles and cools
down.
• The cooler air sinks back to the Earth’s surface, resulting in an area of high
pressure.
• This circular rise and fall of warm and cool air is called a Convection
Current.
• Air also begins to rise and fall again at 60o.
• There are 3 convection currents in each hemisphere.
• Because of the Earth’s rotation, anything that travels a long distance (wind),
appears to change direction.
• This apparent movement is called the Coriolis Effect.
• Imagine throwing a ball to your friend from a moving merry-go
round. It would appear to twist, but in reality it just travels in a
straight line.
Ocean Currents:
• Ocean currents are very similar to Prevailing Winds.
• Water is heated at the equator and it drifts towards the poles.
• Warm water rises to the top and colder water sinks towards the ocean floor.
• This causes warm currents heading towards the poles and cooler currents
underneath the surface, heading back towards the equator.
• The Coriolis Effect still comes into play with ocean currents, but continents
stop the nice patterns from occurring.
• Warm ocean currents heat the air above them.
• Areas with warmer ocean currents will have more rain, and areas with cooler
ocean currents will be cooler and dryer.