Tropical Climate

this lesson talks about tropical environment specially tropical climate which helps to A level Cambridge exam students to prepare themselves

1. Chapter seven Tropical Environment A Level

2. Tropical climates Mr. Yonas Gemeda Addis Ababa 2019

3. Learning outcomes At the end of this lesson students will be able to: Describe about features of tropical environment Define tropical humid climates Classify tropical climates

4. Introduction The tropical environment is the area between 23.5 degree N and 23.5 degree S. There are three types of tropical climate 1. these include rainforest climate 2. monsoon climate and 3.savanna climate

5. Tropical climate characteristics of air mass An air mass is a large body of air in which horizontal gradients of the main physical properties, such as temperature and humidity, are fairly gentle. It applied only to the lower layer of the atmosphere. An air mass can cover an area up to ten thousands of km square.

6. Cont’d Air mass can be modified when they leave their sources. A maritime tropical ( mT ) air mass refers to one that is warm and moist A continental tropical ( cT ) air mass refers to one that is warm and dry. Air mass moves from their source regions they can be changed by the area over which they move.

7. Inter tropical convergence zone The inter tropical convergence zone is an area in the tropics in which the northeast trade winds and the southeast trade winds converge. If there is a difference in temperatures between the winds the warmer air rises over the denser, colder air can produce rain .

8. CONT’D The ITCZ or equatorial trough is a few hundred kilometers wide and lies at 5 degree N. Winds at the ITCZ are commonly light or non existent, creating calm conditions called the doldrums, but there are occasional bursts of strong westerlies .

9. Subtropical high pressure The subtropical high or warm anticyclone is caused by cold air at the tropopouse descending . The main causes of subtropical high pressure belt is cold air at tropopause descending. This is descending air of Hadley cell.

10. Oceanic influence/ oceanic currents The oceanic gyre (swirl of currents) explains why east coasts in the southern hemisphere and west coasts in the northern hemisphereare usually warm and wet, because warm currents carry water polewards and raise the air temperature of maritime areas .

11. CONT’D In contrast cold currents carry water towards the equator and so lower the temperature of coastal areas. West coast tewnd to be cool and dry due to: The advection of cold water from the poles and Cold upwelling currents

12. Wind The temperature of the wind is determined by the area where the wind originates and by the characterstics of the surface over which it is subsequently blows. A wind blowing from the sea tends to be warmer in winter but coolerin summer than the corresponding wind blowing from the land.

13. World climates : classification The most widely used classification of climate is that of W. koppen . His classifacation first appeared in 1900 Koppen classified climate with respect to two main criteria 1. temperature 2. seasonality of rainfall

14. Types Indeed, five of the six main climatic types are based on mean monthly temperature: A. Tropical rainy climate B. Dry C. Warm temperature rainy climate D. Cold boreal forest climate E. Tundra F. Perpetual frost climate

15. Topic revision question 1. define the term: A. tropical humid climate Seasonality humid climate 2. explain about the tropical environment