(10 pt) 3. According to the Held-Hou theory of Hadley circulation, (2 pt) (a) wh
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Question
(10 pt) 3. According to the Held-Hou theory of Hadley circulation, (2 pt) (a) what will happen to the width of the Hadley cell if the rotation rate of Earth were twice as high, that is, 1 day is 12 hours? Calculate the new width (8 pt) (b) Observations showed that over a 30-year period since 1979, the Hadley cell had expanded by~2° latitude. How much higher should the tropopause be to explain the observed expansion? Observations also showed that the tropopause height has been increasing at a rate of 64 m/decade. From your calculation, do you conclude that the Hadley cell expansion has been caused by the tropopause height increase? Why or why not? If not, what other mechanism(s) can you think of that can explain the Hadley cel expansion? Use the following values: = 50K,6,-300K, H= 10 km, =7.3x10-5s-1Explanation / Answer
ANSWER:
The Held-Hou Model is a model for the Hadley circulation of the atmosphere that would exist in the absence of atmospheric turbulence. The model was developed by Isaac Heldand Arthur Hou in 1980.[1]
The essence of the model is that air rising from the surface at the equator conserves its angular momentum as it moves poleward. This distribution of wind, in turn, determines the distribution of temperature, which determines the latitudinal extent of the circulation by requiring energy conservation. This stands in contrast to George Hadley's original conception of the circulation, which he argued reached the poles. The Hadley circulation has a cooling effect at and near the equator and a warming effect at higher latitudes within the Hadley Cell. This energy transport can be converted into a mass transport, to determine the strength of the circulation, by normalizing by the appropriate vertical stability. The effects of moisture and seasons on the model have been studied.
Earth's atmosphere violates the underlying assumptions of the model: angular momentum is not conserved and the tropical atmosphere is not energetically closed.[2] As such, the Held-Hou model is a conceptual model that does not make quantitatively accurate predictions of the sensitivity of the Hadley circulation to changes in atmospheric parameters.
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