Can you predict the weather just by looking at clouds?

9 December

Clouds give very good clues of the immediate status of the atmosphere, and sometimes what’s about to arrive – or not, depending on if it’s a stable condition or if it’s likely to change.

"If you marry up the clouds, the wind and the humidity, you can be your own weather forecaster."

Right now, I’m looking at blue sky, and I know that if I cycled to the gym, I wouldn’t get wet. But there are over 30 different cloud types, though there are three main types according to height, classified as high, medium and low, and some will tell you you’ll have a shower in the next 10 minutes – you can see it coming. Or some higher up, like the very feathery horsetail types, gives an inkling that, in the distance, a warm front is on the way.

You’ll need to know what type of weather each type of cloud represents, but with that information, if you marry up the clouds, the wind and the humidity, you can be your own weather forecaster. That’s where forecasting starts, by observation at a certain time of day.

The experts are all getting their information by observing, at the same time, so we can see the status of the atmosphere and everyone reports it to the World Meteorological Organisation, who maps them together, which is called synoptics. From there, you can make an analysis and draw your pretty maps with all the isobars. It’s always a little bit behind, time-wise, because the next minute, the conditions have changed. But forecasters look at that, and produce a prognosis of what’s going to happen next.

Jim Dale is the founder of British Weather Services.

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