Answers to Everyday Questions : How does the sun affect ocean currents, air currents, fronts, and masses?

How does the sun affect ocean currents, air currents, fronts, and masses?

2 Responses to “How does the sun affect ocean currents, air currents, fronts, and masses?”

1. Michel Verheughe said :
   February 9th, 2011 at 3:56 am

   If we exclude e.g. the geothermic house heating in Iceland, the sun is the source of all energy on earth and it, indeed, affects ocean and atmospheric currents.

   The equator is the warmest place on earth. Here, the sun warms the earth or the sea, which in turn, heats a layer of air right above it, which rises since it is now warmer and lighter. That air then cools down with the adiabatic effect of a lesser pressure aloft and the moisture condenses as it reaches dew point temperature. Clouds form, possibly with precipitations.

   At the poles, the coldest places on earth, the air sinks because cold air is heavier. By the same but opposite adiabatic effect, that air warms up and clouds evaporate, giving place to a clear sky.

   If it wasn’t for the earth’s rotation and the resulting coriolis effect, the air that rose at the equator would probably travel to the poles to sink there. But the coriolis effect diverts to the right hand any slow fluid displacement in the northern hemisphere. As a result, the air rising at the equator comes down, forming two belts of high pressures at roughly latitudes 30 north and 30 south.

   Between those and the poles, a front exists where cold polar air meets milder temperate one. Here again, the warmer air rises over the colder one and that creates a lower pressure with clouds and precipitation. Those frontal lows are roughly at latitudes 60 north and 60 south.

   And that creates the major atmospheric circulations on earth. They are called the Hadley, the Ferell and the Polar cells. Air rises, cools down, sinks, warms up, and so on.

   Likewise, sea currents tend to move to the right hand side in the northern hemisphere, due to the coriolis effect. A good example of both atmospheric and oceanic currents is the north Atlantic.

   At the north, the prevailing wind is westerly because the air spinning counter-clockwise around the lows at 60 N, takes the air eastward. At the edge of the inter-tropical convergence zone in the northern hemisphere, the prevailing winds are then easterly; what we call, the Trade Winds.

   The Azores is also a place of high pressure and works as the center of the clockwise atmospheric displacement around it. It is also the center of the clockwise oceanic current in the north Atlantic where, at the north, the Gulf Stream flows toward Norway, while at the south, the Trade winds current moves toward the West Indies (Caribbean, for the Americans). But, what is not so often known, is that the Trade wind current starts, in fact, in the Bay of Biscay, as a branch of the Gulf Stream. It passes off the coast of Portugal where the current is always southward (note: winds are given as where they come from but currents, as where they go). In fact, it is often referred as the “Portuguese Trades.”

   This then comes back around the Saragossa sea, in the Gulf of Mexico and back in the Gulf Stream, forming a circle in the north Atlantic. Only the branch of the Gulf Stream moving north to the north of Norway, when cold and salty enough, sinks to form a subsea current, heading south to form the Thermohaline Circulation that is also called the Oceanic Conveyor Belt that mixes all the water of all oceans in perhaps a thousand years.
2. Arasan said :
   February 9th, 2011 at 4:36 am

   Air currents or winds are caused by the the pressure gradient(differences in air pressures) between two places which in turn depends upon the temperature gradient.This temperature gradient is the result of the unequal heating of the earth’s surfaces(land as well as sea).Surface ocean currents or warm currents are wind driven and are affected by seasons which are caused by the unequal heating by the solar radiation.Deep currents or cold currents are driven by density(salinity) and temperature gradients.So the main cause of ocean currents are solar heating,gravity(cause by density difference) and winds.
   The property of air depends essentially on temperature and humidity.When a mass of air of substantially the same nature characteristics covers a large area ,it is called air mass.Based on temperature,air masses can be classified equatorial,sub-tropical,sub-polar and polar.The polar and tropical are more important .Based on humidity they can be classified as maritime or continental.The polar air will be colder and the tropical air will be comparatively hotter.This is again due the unequal heating of the equatorial area and polar areas by the solar radiation.The tilt of the earth’s axis causes this difference in temperature .
   When contrasting air masses(in temperature or humidity) lie side by side ,the narrow zone of discontinuity separating the two air masses is called a front.The polar front is an example which lies at about 60 degrees North or South.Warm or cold fronts are caused by the interaction of warm and cold air masses.So, solar radiation is the fundamental cause for ocean currents,different air masses and fronts and air currents and in short is the cause for all weather phenomena that occur over the earth .