8: Oceans and Climate
After reading this chapter you should:
- understand the concept of the heat budget of the earth (you do not need to remember all of the percentages, just general trends)
- know the difference and relative importance of radiation, conduction and phase change in exchanging heat with the atmosphere
- understand the mechanisms and causes of the greenhouse effect and global warming
- understand how evaporation and condensation transport heat in the atmosphere and oceans
- understand how the curvature of the Earth results in differential heating of the surface
- understand the role played by albedo in radiation reaching the Earth
- understand how and why atmospheric convection cells form
- understand the reasons for and the results of the Coriolis Effect
- be able to derive the major wind patterns on Earth
- understand the relationship between climatic zones and convection cells – e.g. why are rainforests along the equator?
- understand the effects of altitude on air masses and climate
- understand how seasonal and daily cycles effect things like land and sea breezes
- understand how hurricanes form
- understand the potential impacts of climate change
The ultimate source of energy driving the motion of the atmosphere and the ocean is radiant energy from the sun, which falls on different parts of the Earth in differing amounts. The oceans are the recipient of most of this solar energy, and they are therefore a major factor in regulating Earth’s climate. Remember that compared to land temperatures, ocean temperatures do not undergo large swings from day to night or seasonally. This is due to a number of factors;
- Water has a very high heat capacity, so it can absorb a large amount of heat without much of an increase in temperature. Water can also release large amounts of heat back to the atmosphere without its temperature declining as much as land temperatures would.
- On land, the solar energy only hits the surface, which can heat up dramatically, but the heat does not penetrate very far below the surface. In water, light penetrates for a few hundred meters, so the heat is distributed through a greater area, and water does not heat up as quickly as land.
- Mixing of water in the top few hundred meters also distributes heat. Mixing does not happen on land.
Because of water’s ability to regulate heat exchange and climate, areas near the oceans usually have a much milder climate than regions in the center of the continents. Furthermore, areas in the Southern Hemisphere have a much more moderate climate than regions of similar latitude in the Northern Hemisphere, because a larger proportion of the Southern Hemisphere is covered by oceans.
In this chapter we will examine the ways that the oceans and atmosphere interact with solar radiation to influence wind and atmospheric circulation, local weather phenomena, and global climatic zones.
Thumbnail: The movement of upper-air water vapor over the Eastern Pacific is shown using GOES satellite air temperature data. High, cold clouds are white. High, cold, clear air (around -28 F) is blue. Lower, warmer, dry air (around -10 F) is magenta (where clear, dry air penetrates lower in the atmosphere). (Public Domain; NASA/NOAA GOES Project Dennis Chesters )