(a) What is the name of weather systems centered about regions of low pressure? (b) In what direction do winds in the northern hemisphere spiral around such a region? (c) In the southern hemisphere?

(a) The weather systems centered around regions of low pressure are called cyclones.

(b) In the northern hemisphere, winds around a low-pressure system (cyclone) spiral counterclockwise. This means that the wind flows in an anticlockwise direction, moving inward towards the center of the low pressure.

(c) In the southern hemisphere, the winds around a low-pressure system (cyclone) spiral clockwise. This means that the wind flows in a clockwise direction, moving inward towards the center of the low pressure.

To understand why winds flow in these directions, we can consider a concept called the Coriolis effect. The Coriolis effect is caused by the rotation of the Earth and influences the direction of moving objects, such as winds. In the northern hemisphere, the Coriolis effect causes moving air to be deflected to the right, which results in the counterclockwise circulation around a low-pressure system. In the southern hemisphere, the Coriolis effect causes moving air to be deflected to the left, resulting in the clockwise circulation around a low-pressure system.