Tropical storms

Question 1

Storms

Answer 1

• occur when there are large diff in atmospheric pressure between 2 areas
• e.g low pressure system in Australia, high pressure system in Central Asia (causes NE Monsoon)
• storms dont just occur during Monsoon seasons
• occur throughout year, due to Hadley cells and ITCZ

Question 2

Hadley Cells

Answer 2

• equatorial regions; area of low pressure due to constant solar energy received (large angle of incidence
• equatorial warm air rises 30 degrees north and south, cools down rapidly, rain(Cloud form)
• concurrently, cooler and denser air at 30N and 30S move towards lower pressure area at equator
• forms stable circulatory system, bring dry and cool air to 30N and S, forming desert conditions; bring winds and storm systems towards equator
• draw annotated diagrams

Question 3

Deserts

Answer 3

-form along Horse latitudes (30N, 30S)

Question 4

Inter Tropical Convergence Zone

Answer 4

• area that is affected by tropical storms, cyclones, hurricanes, typhoons
• area of lowest pressure, where most of world’s storms occur
• receives converging winds blowing frm Hadley Cells from north and south
• not always at equator becos of seasons
• Jan: ITCZ below equator, sun directly over 23S/Tropic of Capicorn
• July: ITCZ above equator, sun directly above 23N/Tropic of Cancer
• can use this to predict times of yr where particular area may have high potential of storms occurring

Question 5

Tropical cyclones

Answer 5

• extreme/severe weather phenomenon
• intense low pressure weather systems that develop over warm oceans in tropics
• strong tropical storms, winds of strong velocity, accompanied by torrential rainfall, cause widespread damage and loss of lives
• move away frm equator
• Atlantic: Hurricanes
• Pacific: Typhoons
• Indian: Cyclones

Question 6

Characteristics of tropical cyclones

Answer 6

• diameter: 100km to 2000km
• may last as long as a month
• speed: 24km/h
• wind speed: 120km/h

Question 7

How and why do tropical cyclones form?

Answer 7

• have sustained speeds of more than 119km/h due to steep pressure gradient
• atmospheric pressure above warm ocean surface very low
• steep pressure gradient result in strong winds spiralling inwards and upwards at high speeds
• warm moist air over ocean expands and rises, then condenses, releases latent heat
• continuous large scale release of latent heat warms air, cause it to expand and rise further
• this reduces air pressure near ocean surface, creating and sustaining area of low pressure at centre (eye) of cyclone
• warm air rises, cools, eventually sinks
• descending dry air creates calm and cloud-free environment in the eye

Question 8

Conditions required for tropical cyclone formation

Answer 8

• warm tropical oceans temp at 26 degrees, depth up to 60m
• low pressure area needs to be far enough frm equator (5-20 N/S) for coriolis effect to create rotation in the rising air mass (too near equator, insufficient rotation, tropical cyclone will not develop)
• need to have low pressure system (unstable air)/depression that has potential to grow (less than 10% tropical disturbances turn into cyclones)
• thus tropical cyclones only found in tropical areas (warm shallow seas like Caribbean)
• once they travel on land/ cooler waters, lose source of energy and strength v quickly