September 12, 2013

It's an inexact science

IF YOU GET your evening news from two separate TV stations, you’ll know that weather forecasting is an inexact science. They seldom agree on the details. And while forecasters don’t often admit it, few forecasts are accurate for more than three days ahead. And no wonder.

Weather is just great spheres of air, huge warm and cold bubbles hundreds or thousands of miles across, jostling fiercely against each other, moving up and down. Who knows where they might go next? If you find yourself at the meeting point of two bubbles (what the experts call a front) you can expect some very interesting weather as they try to beat each other up.

Your barometer measures the atmospheric pressure inside these bubbles. High pressure means a good bubble and nice weather. Low pressure signifies a bad bubble and rotten weather.

So if your barometer is steady, you can expect tomorrow’s weather to be much more like today’s than anything else. If it’s falling, you can expect bad weather. The faster the fall, the sooner it will arrive. If the glass is rising, a good bubble has arrived and fine weather will follow.

You’ll find your barometer just as reliable as a weather fax once you’ve learnt to interpret it, and a lot cheaper.

Incidentally, it’s the speed of the barometer’s rise or fall that determines how quickly and how drastically the weather will change.

Today’s Thought
The best weather instrument yet devised is a pair of human eyes.
— Harold M. Gibson, Chief Meteorologist, NYC Weather Bureau

“May I print a kiss on your lips?” I asked,
And she nodded her full permission.
Well, we went to press,
And I rather guess
We printed a full edition.
— Joseph Lilienthal

(Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)

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