Formation of tropical storms

What happens when a storm has started to form?

It will soon develop its distinct and clearly defined rotation (Coriolis force)

How does a storm start to form?

Warm, moist air rises rapidly in its centre, to be replaced by air drawn in at the surface.

What develops as more air is drawn in and rises?

A central vortex.

The very centre (eye) is often a column of dry, sinking air.

What happens as air rises?

It rapidly cools, which leads to condensation and formation of towering cumulonimbus clouds.

What happens when condensation occurs?

Latent heat is released, which effectively powers the storm.

What happens once a central vortex has formed and condensation has occurred?

The tropical storm continues to grow and develop as it is driven by the prevailing winds across the oceans.

What happens when the storm reaches land?

The supply of energy and moisture is cut off, meaning the storm starts to decay.

What would happen is the storm moved back out over the ocean?

It would become reinforced and grow further.

How is a central vortex actually created?

As air rises and starts to spin.

What happens 15 - 20km above sea level?

Winds spiral outwards.

How are storms categorised?

By the Saffir Simpson scale based on sustained windspeeds developed in 1971.

How does the Saffir Simpson scale categorise storms?

Cat1: 74-95mph

Cat.2: 96 - 110mph

Cat.3: 112-129mph

Cat.4: 130-156mph

Cat.5: 157mph+

What happens as the categories get higher in number?

They became more destructive and harder to prepare for.

What is a weakness of the Saffir Simpson scale?

Are widely used, but does not take into account rainfall, or the area affected by a storm.

e.g. low-cat cyclone hitting a densely populated urban area can be more damaging than a high cat storm in a remote region.

What are the categories for a storm surge created by a storm?

5: >18ft

4: 13 - 18ft

3: 9 - 12ft

2: 6 - 8ft

1: 4 - 5ft

What categorises a tropical depression?

0 - 38mph winds.

What categorises a storm as a tropical storm?

39 - 73mph winds.

What else does the Saffir Simpson scale take into account?

Doesn’t take into consideration forward moving speed.