Forecasting Weather Knowing Past Weather Conditions
Have you ever watched the weather and heard the forecaster say that a low or a high front was moving into your area? Highs and low fronts are gauged by utilizing an instrument called a barometer.
As past weather is an indicator, a falling barometer means air pressure is lessening and a rising barometer means air pressure is increasing. From analyzing the rainfall data, wind speeds and cloud types, we now know that a high pressure area is clear and dry, while a low pressure area consists of rain, wind and cloud cover.
Large, gradual and continual drops in pressure will forecast a long episode of unusually bad weather. Expect the weather to be more pronounced if the atmospheric pressure went up before it started to fall.
Conversely, a large, gradual and continual increase in pressure indicates that an approaching episode of long-lasting good weather is expected. If there is a quick rise in pressure when times are fair and moderate or there is above average pressure, then this means that there is a coming low pressure episode. Scientists gather past weather information in order to understand this phenomenon.
If a long glass tube is filled with mercury and is then stood upright with the opening end pointing downwards into a dish containing mercury, much of the mercury will flow out of the tube until a column of mercury forms.
The air pressure acts upon the surface of the mercury in the dish and is therefore able to hold up a high mercury column. It is experiments like this, along with studies of past weather information such as rainfall data, cloud types and winds speed that allow scientists to predict future weather.
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July 7th, 2010 at 1:14 pm
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