Global Heat Transfer and Atmospheric Circulation

General patterns of ocean surface currents

After the Gulf Stream emerges from the Caribbean, it splits in two, with one part heading north-east to Europe and the other circulating back through the tropical Atlantic. As the north-eastern branch flows, it gives off heat to the atmosphere, which in turn warms European land. The north Atlantic conveyor carries warm water to northern latitudes releasing heat to the atmosphere. By the time it reaches the northern latitudes around Greenland and Iceland, the water has cooled so much that it sinks towards the ocean floor, a process known as "overturning". This cooler water heads south, forming the return stream of a conveyor belt. The complete cycle sees warm water coming northwards on the ocean's surface, and the cold water returning hundreds or thousands of meters underwater.

Ascending air mass - low surface pressure

Ascending Air Low pressure Convergence at surface Divergence aloft

Descending air mass - surface high pressure

Descending Air Convergence aloft High pressure Divergence at surface

Net Radiation Balance

Earth's net radiation, sometimes called net flux, is the balance between incoming and outgoing energy at the top of the atmosphere. It is the total energy that is available to influence the climate.

Geographic regions of surplus and deficit in net radiation

Low to middle latitudes have a net surplus of radiation, whereas high latitudes have a net deficit. Energy deficit at the poles, and energy surplus at equatorial/tropical regions. ... The blue regions indicate that there is more outgoing energy than incoming, yielding a net loss of energy from the Earth's surface.

Global atmospheric circulation cells

One way to see this force in action is to see what happens when a straight line becomes a curve. Picture the Earth as a turntable (see number 1) spinning counter-clockwise. A ruler is placed over the turntable (see number 2) and a pencil will move in a straight line from the center to the edge while the turntable spins underneath. The result is a curved line on the turntable (see number 3).

Global heat transport - tropics to poles

The figure above illustrates the latitudinal distribution of incoming solar radiation and outgoing terrestrial radiation. From approximately 35o N to 35o S latitude (the red area of the graph) there is a surplus of energy as incoming radiation exceeds outgoing. The blue regions indicate that there is more outgoing energy than incoming, yielding a net loss of energy from the Earth's surface. One might ask then why the middle to higher latitudes aren't getting colder through time as a result of the net loss, and the subtropical to equatorial regions getting constantly hotter due to the net gain. The reason is that the energy is redistributed by circulation of the atmosphere and oceans. Heat gained in the tropics is transported poleward by the global circulation of air and warm ocean currents to heat higher latitude regions. Cooler air from the higher latitudes and cold ocean currents move toward the equator to cool the lower latitudes. This process of redistributing energy in the Earth system helps maintain a longterm energy balance.

Global patterns of atmospheric circulation

The gradient of solar radiation from the equator to the poles results in a distinctive gradient of decreasing surface air temperature along the same latitudinal gradient (equator to poles). Because warm air is less dense and expands, the depth of the atmosphere (troposphere) will be greater in the tropics. The result is a pattern of convective circulation, transporting thermal energy from the equator to the poles

Relative importance of atmospheric and ocean circulation on heat transport from tropics to poles

The ocean and atmosphere are connected. They work together to move heat and fresh water across the globe. Wind-driven and ocean-current circulations move warm water toward the poles and colder water toward the equator. The ocean can store much more heat than the land surfaces on the Earth.

Importance of atmospheric and surface ocean circulation

The ocean's global circulation system plays a key role in distributing heat energy, regulating weather and climate, and cycling vital nutrients and gases. Density differences in ocean water drive the global conveyor belt.

Coriolis effect/force

deflects water and wind currents.(A) Water or air moving pole ward from the equator is traveling east faster than the land beneath it and veers to the east (turns right in the Northern Hemisphere and left in the Southern Hemisphere). (B) Water or air moving toward the equator is traveling east slower than the land beneath it and veers to the west (turns right in the Northern Hemisphere and left in the Southern Hemisphere).

Jet Stream

forms high in the upper troposphere between the two air masses of very different temperature. The greater the temperature difference between the air masses, the faster the wind blows in the jet stream. The jet stream is a fast flowing "river" of air flowing from west to east. The 50°-60° N/S region is where the polar jet is located, with the subtropical jet located around 30°N. However, their path is not simple. Just like rivers they meander (just like rivers!). These meanders are known as Rossby Waves.The actual appearance of jet streams result from the complex interaction between many variables - such as the location of high and low pressure systems, warm and cold air, and seasonal changes. They meander around the globe, dipping and rising in altitude/latitude, splitting at times and forming eddies, and even disappearing altogether to appear somewhere else.

Wind (advection)

horizontal air flow Winds blow in response to differences in pressure. Wind speed is determined by the magnitude of the pressure difference over distance, called the pressure gradient