PC1672 Advanced dynamics

2.4 The weather

Even though the Coriolis force is too small to have any noticeable influence on your bath water, on larger scales its effects are very important. It is responsible for many aspects of the motion of the atmosphere and oceans and so our climate and weather both depend on it.

In particular, as air flows into a low pressure area it is deflected to the right by the Coriolis force (in the northern hemisphere). As a result the air starts to circle the centre of the low in an anticlockwise sense (seen from above). In a deep low, very high circular wind speeds can build up near the centre (as happens in the eye of a hurricane).

This means that areas of low pressure are not filled in quickly by air flow from surrounding regions of high pressure. They persist for long enough to drift across the Atlantic (helped by the Coriolis force again) and deposit their rain on Manchester.

Textbook references

K&K 8.5, example 8.10
B&O 7.3
M 11.4
M&T 10.4

Mike Birse
17th May 2000