General Circulation of the Atmosphere

Air Circulation models, three model cells, planetary & local wind are shown here with flexible example.

1. Global Circulation of the Atmosphere 1

2. Submitted To: Md. Anarul Haque Mondol Lecturer Department of Geography & Environment Jahangirnagar University Submitted By: Group: I Member Roll Shahorima Jannati 633 Injamamul Haque 649 Khalilur Rahman 663 Abdul Alim 676 Ayesha Akter 2258 Jahangirnagar University Savar , Dhaka- 1342 Course: 201 2

3. Contents Atmospheric Circulation Spheres of Atmosphere Three model of Atmospheric Circulation 1. Hadley Cell 2.Ferrel Cell 3. Polar Cell The Patterns in Global Air Circulation Season Monsoon Day and Night(Sea breeze and Land breeze) 3

4. The purpose of this presentation is to introduce the topic of atmospheric circulation. Main concepts Atmospheric circulation is a response to differences in insolation between low and high latitudes. There is a transfer of energy from low to high latitudes. A global pattern of surface winds and pressure belts results from this circulation. There is a seasonal shift of the surface wind and pressure belts. 4

5. What is Atmospheric Circulation? The circulation of wind in the atmosphere is driven by the rotation of the earth and the incoming energy from the sun. Wind circulates in each hemisphere in three distinct cells which help transport energy and heat from the equator to the poles. Cyclone 5

6. Troposphere extends to 16-18 km above the tropics but <10 km above the poles; contains ~80% of atmosphere’s mass; and runs the hydrological cycle because tropospheric temperatures decrease with height Average temperature, °C Troposphere Tropopause Stratosphere Mesosphere Thermo-sphere Average atmospheric temperature Stratopause There is a hole in the Ozone layer right above Antarctica Height, above mean sea level (km) Spheres of Atmosphere 6

7. Three model of Atmospheric Circulation Hadley Cell Ferrel Cell Polar Cell 7

8. Hadley cell The Hadley cell, named after George Hadley, is a global scale tropical atmospheric circulation that features air rising near the equator, flowing poleward at 10–15 kilometers above the surface, descending in the subtropics, and then returning equatorward near the surface. This circulation creates the  trade winds , tropical rain-belts and hurricanes, subtropical deserts and the jet streams . 8

9. The Ferrel cell occurs between 30 and 60 degrees north and south. The Ferrel cell is dependent for its existence upon the Hadley cell and the Polar cell. It comes about as a result of the high and low pressure areas of the mid-latitudes. For this reason it is sometimes known as the "zone of mixing." In this cell at higher levels the wind blows equatorward and in a westerly direction and pole wards and in an easterly direction on the surface.  Ferrel cell 9

10. This cell occurs at 60 degrees north and south. The air has been warmed up and rises upwards, creating a zone of low pressure. Though cool and dry relative to equatorial air, air masses are still sufficiently warm and moist to undergo convection. When the air reaches the polar areas, it has cooled considerably, and descends as a cold, dry high pressure area, moving away from the pole along the surface. Polar Cell Polar cell 10

11. Interaction with each other cells 11

12. Describe atmospheric circulation with picture 12

13. The Patterns in Global Air Circulation 13

14. Trade Winds Trade winds blow in a belt lying between 5N-30S in the southern hemisphere. Polar Easterlies The polar easterlies blow from the polar high pressure area to the temperature low pressure area. Westerlies The westerlies winds blow across latitudes 35-60 of both hemisphere. Westerlies Westerlies Polar Easterlies Polar Easterlies Trade Winds Trade winds, Westerlies, Polar Easterlies 14

15. Atmospheric Circulation is difference in Seasonally 15

16. Monsoon Monsoon is traditionally defined as a seasonal reversing wind accompanied by corresponding changes in precipitation, but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with the asymmetric heating of land and sea. Rain 16

17. Example 17

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19. Conclusion Atmospheric circulation is the large-scale movement of air by which heat is distributed on the surface of the Earth. The circulation of wind in the atmosphere is driven by the rotation of the earth and the incoming energy from the sun. Without atmospheric circulation earth is static.   19

20. www.google.com www.wikipedia.com www.sciencedaily.com/terms/atmospheric_circulation.htm https://www.youtube.com/watch?v=WXuGYSM2D8k www.dictionary.com www.britannica.com Class Lecture Further Read 20

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