‘March winds and April showers bring forth May flowers.’ Most of us are familiar with the term, but how can April have so many showers and still be one of the year's driest months?
A time of change
April is a month in transition; the long, cold winter days start to wane, and the jet stream – a band of strong winds – begins to move northwards. The chilliness of the dark months is replaced with warmth and light, but so too low pressure and, as a result, the skies open.
But there is more to our April showers than just low pressure. At this time of year, the temperature of the sea is at its lowest. Lengthening days and warming weather result in a significant increase in daytime heating. And it is this disparity – between the warm land and cold sea – that causes shower clouds to form.
How can a month be so wet yet so dry?
So, April showers really do exist. It may, therefore, be a little confusing to learn that it is one of the driest months of the year. In 2016, the Met Office recorded 179.6mm of rainfall in January, compared to just 81.6mm in April. And in August of the same year, the rain gages registered 88.4mm. Indeed, most of the UK’s rain falls between October and January.
There is a reason for all this confusion, of course. The answer lies in the terminology: rain and showers are not the same thing.
So, what is the difference rain and showers?
Rain is precipitation that falls from a weather front – a boundary between two bodies of air. Often stretching over hundreds of miles and comprising various cloud types, these fronts result in precipitation falling over wide areas, often for many days.
Showers, in contrast, are produced by cumulus or cumulonimbus clouds. In spite of their impressive appearance, their scale is dwarfed by that of a front, and precipitation will seldom last longer than a few hours.
For more information on UK weather, visit the Met Office.
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