1. Quick Questions
Describe and explain the weather associated with a winter anticyclone in the British Isles.(8)
Outline the origin of depressions affecting the British Isles (8 marks)

2. Tropical Climates Complete the map for… Equatorial Tropical Monsoon
Tropical Continental
P78

4. Describe the climate (using data) for the 3 graphs.
Singapore – Equatorial
Kolkata – Monsoon
Darwin – Wet/Dry (Tropical Continental)

5. Tropical Climates
Equatorial – Day and night are both around 12 hours and the annual temperature range is small, as low as 3 C. Mean monthly temperatures are C. The diurnal range is greater then the annual range. Night time temperatures may fall to 18 C whereas daytime temperatures may reach 35 C. With high humidity and constant temperatures this may be oppressive. Rainfall is high over 2000 mm per year with a predictable daily pattern that varies little over the year
Tropical Continental (wet/dry) - There is a hot wet season with temperatures above 26 C and heavy convectional rain. Rainfall is greatest nearer the equator, 1,200 mm per year, lowering as you move away from the equator. For the rest of the year there is a hot dry season. Temperatures range from 40 C in the day to 10C at night
Tropical Monsoon – There is a very clear rainy season (Jun-Sep) when over 300mm of rainfall fall in each of 3-4 months). The rest of the year is very dry. Temperatures are hot all year, but dip slightly in Nov-Feb. Then, the temp is around 20 C from a peak high over just over 30 C

6. ITCZ – How does the movement of the ITCZ cause the 3 types of climate?

12. The ITCZ's location varies throughout the year and while it remains near the equator, the ITCZ over land drifts farther north or south than the ITCZ over oceans. This is due to greater variation of land temperatures. The location of the ITCZ can vary as much as 40° to 45° of latitude north or south of the equator based on the pattern of land and ocean. Despite these variations the ITCZ relates closely to the altitude of the sun and marks the point where the sun is highest in the sky. In temperate latitudes relative migration of the sun between the Tropic of Cancer and Tropic of Capricorn is responsible for creating the seasons but in tropical latitudes it is responsible for the migration of low pressure and the resullting shifts in seasonal tropical rains. The ITCZ and converging trade winds can be seen in the graphic below. The animation shows the shifting seasonal rains follow the the movement of the ITCZ.

13. In addition to the ITCZ there are a number of other climate controls that influence the types of climate in the tropics. The influence of land and sea has a critical affect on the migration of the ITCZ. Due to the heat retention and stability of temperature within the ocean the ITCZ remains more anchored to one position over oceans. In contrast land temperature vary over the year and temperature is also influenced by altitude and relief. These factors create greater ITCZ migration and climatic variation north and south over continents. In Tropical Monsoon Climates the ITCZ can interact with other climatic patterns such as offshore winds that form as a result of deep lows over land. In combination with the ITCZ this helps produce enormous seasonal rains.

14. The second distinctive climate feature of tropical regions is the dry season. As you can see from the diagram to the right of the Hadley circulation air rises above the ITCZ to create a low pressure zone, characterised by high humidity and rainfall. Further north and south of this zone air begins to sink. As air sinks it becomes warmer. Remember warm air can hold much more water vapour than cold air. As a result of its warming its relative humidity falls and moisture gets locked inside the warm air. The air continue to sink warming further. The resulting atmospheric conditions are hot, dry, calm and clear skies with high pressure, called Tropical Anticyclones.T heoretically there is more moisture in the air at these latitudes than above the British Isles but you just can't see it. Over time the ITCZ migrates north and south and with it we see the migration of the warm dry highs.

15. Why are these people wading through the water?

16. Why are these crops so plentiful?

17. Persistent Circulation Patterns NH winter
Sea level pressure and prevailing winds 17

18. Persistent Circulation Patterns NH winter
> subtropical highs
Sea level pressure and prevailing winds 18

19. Persistent Circulation Patterns NH winter
> 2 major subpolar lows: near polar front, storm track
Sea level pressure and prevailing winds 19

20. Persistent Circulation Patterns NH winter
> subpolar highs: shallow, thermally induced
Sea level pressure and prevailing winds 20

21. Persistent Circulation Patterns NH winter
> subpolar trough in SH: high winds and seas, roaring 40s
Sea level pressure and prevailing winds 21

22. Persistent Circulation Patterns NH winter
> ITCZ displaced south
Sea level pressure and prevailing winds 22

23. Persistent Circulation Patterns NH summer
> ITCZ displaced north
Sea level pressure and prevailing winds 23

24. Persistent Circulation Patterns NH summer
> Subtropical highs move north
Sea level pressure and prevailing winds 24

25. Persistent Circulation Patterns NH summer
> Thermal lows develop over land
Sea level pressure and prevailing winds 25

26. Persistent Circulation Patterns NH summer
> Weak Icelandic Low remains, Aleutian Low disappears
Sea level pressure and prevailing winds 26

27. Persistent Circulation Patterns NH summer
> Asian Monsoon season
Sea level pressure and prevailing winds 27

28. Seasonal Circulation Patterns
winter
summer
Subpolar lows disappear
Subtropical highs remain
Zone of max heating shifts north Weak equator - pole temp gradient
Strong thermal imbalance Strong pressure gradient
Strong winds Strong equator - pole temp gradient
Thermal Imbalance is the Driver
Sea level pressure and prevailing winds 28

29. Other Factors
The Himalayas are so tall, they cause massive uplift and the moist air forms clouds that bring heavy rain.
Just before the rain, the Tibetan plain is warmed and this gives rise to strong Easterly winds I the high atmosphere. This is crucial in allowing the full rise of the oncoming air up and over the mountains

31. The Monsoon

33. Seasonal Circulation AnimationH
Sea level pressure and winds University of Oregon
Thermal Imbalance is the Driver 33

34. January (N.Hem Winter) ITCZ moves South due to the earth tilting the South towards the sun, making the hottest point South of the equator

35. July (N.Hem Summer) ITCZ moves North of the equator due to Earth tilt

38. Monsoon Good?
NEW DELHI: India's south-west monsoon is likely to be normal for the second straight year in 2011, weather officials said on Monday, raising hopes of higher farm output that could help the government tame high food prices.
The monsoon acts as a lifeline for India's farm-dependent economy, which is also the world's leading producer and consumer of several key commodities such as sugar, grains, oilseeds and cooking oils.
"There is no abnormal global signals in the weather system to hint that there could be a drought this year," D. Sivananda Pai, director at the state-run National Climate Center, told Reuters.
Pai said a La Nina weather pattern, which causes heavier-than-normal rains in South Asia, still prevails over 25 percent of the country and is expected to remain active till May, just before the start of the June-Spetember monsoon season.

39. Another senior official said weather models of the Indian weather office ruled out chances of occurrence of El Nino that causes drought conditions in the Indian sub-continent.
"Our statistical models do not forecast a bad monsoon for 2011," the government official said without wanting to be named.
India's main weather office will come out with its first forecast on this year's monsoon season in April with periodic reviews as the four-month season progresses.
The government in Asia's third-largest economy is struggling to control double-digit food inflation, among the highest in the region, and a good monsoon is seen as crucial for higher farm output needed to cool prices.
Prime Minister Manmohan Singh, whose Congress party faces several important state elections this year, has said fighting inflation is a priority and last month's federal budget has spelt out steps to help boost farm output.

40. Monsoon Bad?
In July and August 2010, abnormally heavy monsoon floods hit the Indus River in Pakistan, causing unprecedented damage. The floods deluged a fifth of the country, affecting 21 million people and destroying homes, farmland, health clinics, power stations, schools, roads and water-supply systems. The scale and damage of the floods is greater than that of the Asian Tsunami, the Kashmir earthquake and the Haiti earthquake combined.  

41. Six months later, on January 31, the Pakistan Federal Government called an official end to relief operations. But the disaster is far from over. Millions continue to need humanitarian aid, with deeper effects to come. Many areas – mainly houses and agricultural land – remain under water or cut off. Over one million people (and probably many more uncounted) are still homeless, with no adequate shelter for the winter. In southern Pakistan, malnutrition rates, already critical before the flood, now rival those of African countries affected by famine, UNICEF estimates  

43. Assess the relative roles of sub-tropical anticyclones and the inter-tropical convergence zone in creating the characteristic features of the climate of one tropical region that you have studied. (40 marks)