Monsoon wind - resource pack

Northeast- northwest monsoon

Explain why Delhi receives very light rainfall in Fig. 4.                                                  [4]

-        Delhi receives light rainfall due to northeast monsoon (October – February)

-        an area of high pressure forms overs Indian sub-continent and Central Asia while an area of low pressure forms over Australia

-        due to differences in pressure between the northern and southern hemispheres, air moves from Central Asia down towards Indian sub-continent

-        resulting in drier and colder winds that bring with it light rainfall as they blow across cold land to Delhi

Southwest-southeast monsoon

With reference to Fig. 6, explain how Mangalore, India is affected by Southwest monsoon.  [4]                                                                                              

·        Max 3 marks awarded only if student never make reference to Mangalore, India.

·        Between June and September, when it is summer in the northern hemisphere.  Air over Central Asia heats up, expands and rises, forming a region of low pressure over the area. 

·        During the same period, the southern hemisphere is experiencing winter.  The low temperature causes the air to be cold and dense, exerting a greater force on the earth’s surface.  This results in an area of high pressure over Australia.

·        Due to the difference in pressure between Central Asia and Australia, air from Australia moves to the Indian sub-continent and Central Asia as the southeast monsoon winds.  As the winds cross the Equator, the Coriolis effect deflects the winds to the right. 

·        These winds become the southwest monsoon winds and warm up as they head for Central Asia.  The warm air picks up moisture as it travels over the Indian Ocean and brings heavy rain to the Mangalore, India.  

Videos - Monsoon

coriolis effect Monsoon winds

Common test answers

1	(a)	Explain why different places experience different temperatures with reference to their latitudes.                                                                                                                          [5] -        Temperature differs between places at lower latitude and higher latitude because the sun’s rays/solar radiation strike various parts of the world at different angles. -        When the solar angle is higher, the sun’s rays are more concentrated on the area. -        This results in higher temperature eg near to the equator. -        When the solar angle is lower, the solar energy is spread out over a wider area. -        This causes temperatures to be lower eg north and south poles. Wrong answer : Altitude/ distance to sea : Sharifah, Nadia, Xuan Chan, Armin, Enzo, , Kaiwen, Chikin, Yingxuan, Wai Teng
	(b)	Study Fig. 1 which shows a weather instrument used to collect data on rainfall. A ( Outer casing) /   Container - Not measuring cylinder because there's no indication of numbers on it. B (Funnel) C (Glass bottle) Fig. 1
		i) Name the weather instrument in Fig. 1.                                                                          [1] Rain Gauge
	(c)	Study Fig. 2 which shows the formation of rainfall.
		i) With the aid of Fig. 2, explain how precipitation occurs.                                               [4] -        The sun’s energy heats up the earth’s surface intensely and causes air to expand and rise. -        As the air rises, it cools. Air temperature reaches dew point temperature and condensation occurs. -        Cumulonimbus clouds are formed. -        When water droplets become large and heavy enough, they fall to the ground as convectional rain. Good answers: Larry, Jon, Enzo, Armin, Xuan Chan, Sharifah, Wai Teng, Phoebe, Tasmin, Chermaine Perfect score: Anna
	(d)	ii) Using an annotated diagram only, explain the formation of relief rain.                                 [5]
		Diagram (2m) -        Windward side -        Leeward side -        Wind direction -        Clouds and rainfall Explain (3m) -        Warm, moist air from the sea is forced to rise due to heating from the sun. -        Air cools when rises, and at dew point temperature condensation occurs. This forms clouds. -        When clouds are too heavy, it falls as rain on the windward side. note: Many did not say 'fall as rain on the WINDWARD SIDE'. Question is quite well answered in general
	(e)	Define the term ‘Relative Humidity’.                                                                                   [1]
		-        Ratio between the actual amount of water vapor present in a mass of air and the maximum amount of water vapor the air can hold at a given temperature. Note : a number of u did not write 'max amt' or 'can hold. Some of u wrote abt relationship of temp and pressure (higher at lower temp) - Qn is not asking abt rship, only need definition.'
	(f)	Study Fig. 3 which shows a relative humidity conversion table. Fig. 3
		i) Explain how the conversion table in Fig. 3 is used to calculate the relative humidity of a place.                                                                                                                               [3]                                                                                                                            -        Read the dry and wet bulb temperature of the sling psychrometer. -        Obtain the depression of the wet bulb by using the dry bulb minus the wet bulb temperature. -        Find the value at which the dry bulb temperature intersects with the depression of the wet bulb. The relative humidity would be measured in percentage.
		ii) Students were using the sling psychrometer in school to measure the relative humidity of the classroom. Describe 3 common errors that the students may make which cause the data collected to be inaccurate.                                                                                                      [3] -        Students may forget to dip the wick in water. -        The wick may not be fully saturated at the start of the experiment. -        Students may not swing the sling psychrometer at a consistent speed. -        Students may read the temperatures wrongly due to parallax error. -     Students may hold the sling psychrometer too close to the body which may affect the temperature -     Students did not swing for up to 1 min/ swing for more than 1 min