Formation + Development Of Cyclones, Hurricanes, Tyohoons + Tornadoes

Question 1

Formation of hurricanes

Answer 1

• form in warm oceans = needs to be warm to at least 60m - 28°C at the surface
• evaporation from ocean surface = warm air rising + cooling creates ‘unstable air’ + pre-existing winds start the spin
• instability caused by release of latent heat by condensation
• release of latent heart boosts the uplift
• pre-existing winds have to be from same direction + same speed all the way up + air must be moist up to 5500m for more latent heat to be available (these two conditions are unusal)

Question 2

Where do hurricanes form + why?

Answer 2

• hurricanes form less than 5° North from the equator
• otherwise the corislis effect is too weak to generate the rotation needed

Question 3

Formation of a tornado

Answer 3

• warm moist air meets cold dry air
• strong wind sheer in upper atmosphere + jet streams present = leads to formation of a thunderstorm
• within the storm, air starts to spin due to coriolis effect = creates ‘supercell’ within the cloud
• due to wind shear, the supercell tilts + down draughts of cooler air form, these act to pull a vortex down from the clouds towards the ground + cause the supercell to tighten + become more intense
• if/when the descending vortex reaches the ground it forms a tornado

Question 4

Where do tornadoes occur?

Answer 4

• strip of North American Great Plains from Texas to South Dakota is known as ‘tornado valley’
• the only other country to have tornadoes on this scale is Bangladesh = warm moist air from Bay of Bengal