High pressure or an ‘anticyclone’ usually brings a variety of
settled, dry weather, depending on the season. During winter the
weather under high pressure over the UK can be often cold and
cloudy during the daytime with nights often cold enough to allow
frost to form. Whilst in summer it can cause days to be warm and
sunny with nights being often mild, sometimes warm enough to
make sleeping very uncomfortable. Anticyclones form when air
subsides, falls, unlike low pressure which forms when air rises.
As air subsides it gradually warms, this warming can stop clouds
from forming. However if there is some warm air located near the
ground, some air may rise and form areas of patchy or high
cloud. Anticyclones can be slow-moving and sometimes stubborn to
clear. Any depressions which try to get to close to it may
circulate around it and dump bad weather somewhere else. With
high pressure, winds are lightest at the centre and circulate
clockwise in the northern hemisphere and counter-clockwise in
the southern hemisp