The air continues to rise up to the upper atmosphere, and the following then happens: The air separates and starts to move both north and south towards the poles. As the air sinks, it becomes warmer and drier. This creates an area of little cloud and low rainfall, where deserts are found. The Hadley cell is then complete. The air completes the cycle and flows back towards the equator as the trade winds. In the northern hemisphere, the winds flow to the right and are called northeast trade winds.
In the southern hemisphere the winds flow to the left and are called the southeast trade winds. This is down to the Coriolis force and friction. This change would increase the poleward moving air's Rossby number. The Rossby number describes the importance of the Coriolis force in atmospheric dynamics. A higher Rossby number means that the Coriolis force has a smaller impact on a particle, so if the height of the tropopause increased enough, the Rossby number would become high enough to make the Coriolis force negligible.
As a result, particles would not diverge from their path as they moved poleward, and the Hadley Cells would reach the poles. There temperature increases would almost double the static stability at the tropopause. For the height to increase, the stratosphere would also have to become less stable. If CO 2 concentrations increased and if stratospheric ozone concentrations decreased, the stratosphere would cool substantially, and this change would destabilize the stratosphere.
As a result of the alterations to tropospheric and stratospheric stability, the tropopause height would increase. Farrell estimates the height would have doubled under Cretaceous conditions, and as a result, the Rossby number would have doubled.
This change would have allowed the Hadley Cells to extend to the poles and would have made equable climates more likely. Hadley cells could extend all the way to the poles. While each of these alterations to the atmosphere would extend the Hadley Cells, Farrell found that a combination of the two effects was necessary to make his model's results agree with proxy data from equable climates.
He graphed the atmosphere's potential temperature versus latitude at different tropopause height and friction values. The results reveal that as tropopause height and friction increase, the EPTD decreases. The location of mid-latitude storm tracks are marked with an L. The location of the jet stream is marked with a dot.
The left side of the chart depicts the Southern Hemisphere; the right side depicts the Northern Hemisphere. The cloud data was collected by CloudSat. Some of the effects of this are pretty straightforward: more carbon dioxide in the atmosphere means air temperatures will rise; ice in the high latitudes will begin to melt ; and sea level will rise.
That seems pretty straightforward, right? But there are some areas where the changes will be more complicated. For instance, what will all of that extra carbon dioxide means for how air circulates, for the position of the jet stream, and for how clouds are distributed in the atmosphere? In case you are not familiar with some of the scientific terms, I have added links to web sites that explain them in more detail.
I also added some additional explanations to make his description a little clearer. Atmospheric circulation, when examined using a simplified, two-dimensional view such as the figure above , is dominated by two major features. The first is a large feature called the Hadley cell , which lifts air in the Inter-Tropical Convergence Zone ITCZ , moves it at high altitudes towards the poles, and sinks it again to the surface in the subtropical regions.
Active 2 months ago. Viewed 4k times. Improve this question. Community Bot 1. Add a comment. Active Oldest Votes. Improve this answer. But according to that explanation the most reasonable way to go forward with the calculation would be to calculate the width of the cell the distance the N-S wind can travel before becoming E-W.
But instead you assume that there must be a number N of cells of equal size. Why is that? Why all cells should be of equal size? One can of course take into account how the coriolis factor changes with planetary latitude, but then the formula for the number of cells per hemisphere becomes an implicit equation.
How much is it changing on Earth?
0コメント