1.2 Hurricane spin

(source: http://www.weatherquesting.com/hurricane-spin.htm)

A hurricane is a system of violent thunderstorms with high winds circulating about a central low-pressure area, called the eye. Air pressure flows from higher pressure towards lower pressure, although not in a straight line because the Earth’s surface spins at different speeds (faster at the equator, slower near the poles); instead, it spirals inwards (see Figure 1).

Figure 1: Counter-clockwise spin of a Hurricane (source: NOAA, USA).

In the Northern Hemisphere for example, higher-pressure areas from the north, west, east and south will move towards a low pressure centre (L in the above diagram).

The air to the north moves eastward slower than the low-pressure area while the air to the south moves faster than L. The different speeds cause the air to circulate counter-clockwise about the low.