Monsoon Wind affecting Hong Kong, India & N. Australia

1. Monsoon Wind affecting Hong Kong, India & N. Australia

2. Monsoon Seasonal reversal of wind direction

3. cold air sinks hot air rises heated ground surface cooled ground surface Low pressure near the ground High pressurenear the ground Relationship bwteen temperature & pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . hot air expands cold air contracts

4. What is the relationship between temperature and pressure ? When air is cooled, air contracts andsinks. When air isheated, airexpandsand rises. As the air near the ground becomes less dense / lighter , As the air near the ground becomes denser / heavier , the airpressurebecomes lower. the air pressure becomes higher.

5. High pressure High pressure 30°N Cooler air contracts and sinks 30°S Cooler air contracts and sinks Wind blows from high pressure areas to low pressure areas Low pressure 0° Hot air expands and rises

6. Factors affecting wind direction 1. Pressure gradient force Wind blows from high pressure areas to low pressure areas. 2. Coriolis force (created by the rotation of earth) Winds are deflected to the right in the northern hemisphere and to the leftin the southern hemisphere.

7. What is monsoon ? The word monsoon is derived from the Arabic word for “a season”. It refers to theseasonal reversal of wind direction. Its results from thedifferent rate of heating and cooling between land and sea, and thepressure difference between large land massesin northern and southern hemisphere in various seasons. summer:land is hotter: lower pressure over land sea is cooler : higher pressure over sea wind blows from sea to land as onshore wind Land heats up and cools down more quickly than the land. winter :land is cooler : higher pressure over land sea is warmer : lower pressure over sea wind blows from land to sea as offshore wind

8. Earth’s Revolution In winter solstice, overhead sun lies on Tropic of Capricorn In summer solstice, overhead sun lies on Tropic of Cancer In vernal & autumnal equinoxes, overhead sun lies on the equator 21 Mar 0° 22 June 23½°N 23½°S 22 Dec 0° 23 Sept

9. 23½°N June L onshore SE monsoon warm, moist (Tm) onshore SW monsoon H offshore SE monsoon cold, dry (Pc)

10. In June, the overhead sun lies on Tropic of Cancer (23½°N). It is winter in Australia. High pressure develops over Australia. Yet, it is summer in China. The land is intensely heated. So, low pressure develops over the Mainland. Since winds blow from high pressure areas to low pressure areas, wind blows from Australia to the mainland China. According to Coriolis force, winds are deflected to the left in the S. hemisphere. So, in N. Australia, winds blow offshore in a northwesterly direction. After crossing the equator, winds are deflected to the right in the N. hemisphere. They blow onshore as SW monsoon in India. On the Asian continent, since South China Sea heats up slowly, pressure is relatively higher than that of the Mainland. So, winds blow onshore from the sea to Hong Kong and S. China as onshore SE monsoon. SE Monsoon (H.K.) in summer

11. 23½°S December H NW monsoon NE monsoon cold, dry (Pc) NW monsoon L warm, moist (Tm)

12. In December, the overhead sun lies on Tropic of Capricorn (23½°S). It is winter in China. The land is intensely cooled. High pressure develops over China. Yet, it is summer in Australia. So, low pressure develops over Australia. Since winds blow from high pressure areas to low pressure areas, wind blows from China to Australia. According to Coriolis force, winds are deflected to the right in the N. hemisphere. So, in S. China, winds blow offshore in a northwesterly direction. In India, winds blow offshore in a northeasterly direction. After crossing the equator, winds are deflected to the left in the S. hemisphere. They blow onshore as NW monsoon in Australia. NW Monsoon (H.K.) in winter

13. 2002#1 Describe how air massses affect the climate in monsoon Asia. In terms of atmospheric circulation, explain the different climatic characteristics of the Inter-tropical Convergence Zone and the Polar Front in the western Pacific region. I. Introduction II. Content A. Climate of monsoon Asia B. Comparison of climatic conditions in tropical regions & temperate regions in relation to wind III.Conclusion 9 18

14. Tm Indian Ocean or Pacific Ocean hot + wet N. Asia Pc Cold + dry I. Introduction 1. delimit monsoon Asia 2. def. monsoon II. Content A. How air masses  climate of monsoon Asia

15. 2001#2 Geographers commonly use the term “monsoon Asia” refers to a region in Asia with seasonal shifts of wind patterns. Describe the spatial extent of the monsoon over the Asian continent and explain how they are formed. Discuss the impacts of monsoons on the weather and farming activities in South China.

16. Essay outline : 2001 #2