I would like some information about isotherms and isobars. I am doing a long term project on them. I am taking temperatures of my back yard for thirty days. Thanks.

Weather forecastors use terms like isotherm and isobar quite often. To understand what they mean you can break the word down into two parts. The prefix "iso" means equal or constant. The root "therm" means temperature. When you put them together you get an isotherm, which is a line of constant temperature. The same works with isobar--the root "bar" means weight or pressure. An isobar is a line of constant pressure. There are many other terms like these which are known collectively as "isopleths".

Isotherms and isobars, plus other isopleths, are very helpful for weather forecasting. If you look at a map that just shows temperature for different cities, you won't be able to see the full pattern of the weather system. By looking at isotherms, it is easier to see there the temperature changes fast or where it doesn't change that much.

Isobars help you see what sort of weather system is in the area. In general, a low pressure system is accompanied by clouds and wet weather and a high pressure system is accompanied by sunny skies and dry weather. Also, you can get and idea of the wind patterns by looking at isobars. The wind generally blows counter-clockwise around a low and clockwise around a high.

Submitted by Dan (New York, USA)
(May 22, 1998)

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