Atmospheric Global Circulation is the movement of air caused by solar energy and the interaction of warm and cold air - this convergence forms cells or belts over the Earth’s surface. George Hadley (1685–1768) a British physicist and meteorologist, who first described this theory in 1753, did so using what is known as the Single-Cell Atmospheric Global Circulation Model or Hadley Cell (The Editors of Encyclopædia Britannica, 2007). Hadley’s Single-Cell theory failed to consider the Coriolis Effect which prevents air from traveling directly to the poles and could not explain the westerly winds in the mid-latitudes (The Editors of Encyclopædia Britannica, 2007). In the 1850’s research provides greater insight to the westerlies and polar easterlies,
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These winds converge within the intertropical convergence zone (ITCZ) near the equator at the doldrums (The Editors of Encyclopædia Britannica, 2012) or as described by William Ferrel (1890) “a belt of calms extending around the globe, where not interfered with by abnormal disturbances or forces”. Whereby, warm air rises, a low pressure system forms, clouds and heavy rain are frequent, and wind is often mild (Department of Hydrology and Atmospheric Sciences, 2013). The air becomes cooler as it ascends closer to the tropopause at which, the air forks toward both the north and south poles. Applying the rotation of the Earth to the air under controlled circumstances – a constant surface temperature and no tilt; viola, Hadley’s theory gave westerly movement to the air and once again had them converging at the equator. What Hadley’s theory missed, however, was how far the winds traveled before returning to the surface to perform its cyclical ritual. Falling far short of the Polar Regions, cool air makes its way back to the surface much sooner; sinking down it becomes clear, warm, and dry near 30° latitude of both hemispheres. Divergence occurs again at the surface, this time the air warms as …show more content…
While Hadley’s theory is far from exact, it has maintained its place in the current 3-Cell Atmospheric Global Circulation Model and continues to be used as a teaching tool. Furthermore, a case study revealed Hadley’s theory is indeed possible, “[a] weak stratospheric circulation may produce a Hadley cell that extends to the pole” (Bordi, I., Fraedrich, K., Lunkeit, F., & Sutera, A., 2007), but only under certain condition and requires the cell to pass over the Ferrel and Polar cells and through the stratosphere (Bordi et al., 2007). Coincidentally, Reis et al. (2006) find that a single Hadley Cell stretches from the equator to the poles when rotation is increased to 144 and 360 hours per day. Could it be that in the one hundred years between Hadley and Ferrel that the patterns had changed that drastically? This would mean that at some point, Earth’s rotation was much faster; even faster than Jupiter. Reis et al. (2006) say it’s not likely since the study of global circulation and rotation rate suggests that the earth’s rotation rate determines the proportionate meridional
These winds converge within the intertropical convergence zone (ITCZ) near the equator at the doldrums (The Editors of Encyclopædia Britannica, 2012) or as described by William Ferrel (1890) “a belt of calms extending around the globe, where not interfered with by abnormal disturbances or forces”. Whereby, warm air rises, a low pressure system forms, clouds and heavy rain are frequent, and wind is often mild (Department of Hydrology and Atmospheric Sciences, 2013). The air becomes cooler as it ascends closer to the tropopause at which, the air forks toward both the north and south poles. Applying the rotation of the Earth to the air under controlled circumstances – a constant surface temperature and no tilt; viola, Hadley’s theory gave westerly movement to the air and once again had them converging at the equator. What Hadley’s theory missed, however, was how far the winds traveled before returning to the surface to perform its cyclical ritual. Falling far short of the Polar Regions, cool air makes its way back to the surface much sooner; sinking down it becomes clear, warm, and dry near 30° latitude of both hemispheres. Divergence occurs again at the surface, this time the air warms as …show more content…
While Hadley’s theory is far from exact, it has maintained its place in the current 3-Cell Atmospheric Global Circulation Model and continues to be used as a teaching tool. Furthermore, a case study revealed Hadley’s theory is indeed possible, “[a] weak stratospheric circulation may produce a Hadley cell that extends to the pole” (Bordi, I., Fraedrich, K., Lunkeit, F., & Sutera, A., 2007), but only under certain condition and requires the cell to pass over the Ferrel and Polar cells and through the stratosphere (Bordi et al., 2007). Coincidentally, Reis et al. (2006) find that a single Hadley Cell stretches from the equator to the poles when rotation is increased to 144 and 360 hours per day. Could it be that in the one hundred years between Hadley and Ferrel that the patterns had changed that drastically? This would mean that at some point, Earth’s rotation was much faster; even faster than Jupiter. Reis et al. (2006) say it’s not likely since the study of global circulation and rotation rate suggests that the earth’s rotation rate determines the proportionate meridional