What constitutes high and low barometric pressure?
2007-10-23 01:42:48 · 4 answers · asked by mcguimt1 1 in Science & Mathematics ➔ Weather
A low is a region in which mean sea level pressure decreases from the periphery to the centre.The winds blow in an anti-clockwise direction(N.H).Cloud formation and precipitation are likely to occur.
A high is a region where the mean sea level pressure increases from the periphery towards the centre.Winds blow in a clockwise direction(N.H).Weather is usually fair.
2007-10-23 06:51:15 · answer #1 · answered by Arasan 7 · 0⤊ 0⤋
A very good question.
There really is no set values. The mean sea level pressure is 29.92 inches of mercury. Some believe any value that is above that is high pressure and any below that value is low pressure.
What really is more accurate is to look at a analyzed surface weather map that shows the isobars (lines of equal pressure) and look for nice circular rings (sort of like a target).
Most surface maps are in millibars (mb) and each isobar (line of equal pressure) is spaced an equal number of mb's apart. When the numbers increase to the center, that is a high pressure center. When they decrease towards the center, it is a low pressure center.
Barometric pressure is a measure of the mass of air that is above that particular location on the map. High pressure means more mass, low pressure means less.
Generally, High pressure means good weather with mostly sunny/clear skies. Low pressure may mean clouds, and rain and other stuff.
2007-10-23 05:14:36 · answer #2 · answered by Water 7 · 0⤊ 0⤋
You are probably thinking of pressure systems, which are referred to as Highs and Lows. This has very little to do with the actual pressure reading - there is no definitive cut off point to say this is High and this Low, it is to do with the direction of the windflow around the centre of the pressure system. In the Northern hemisphere, a Pressure system is referred to as a Low when the air circulates in an anticlockwise direction, and a High when it is clockwise. Pressure readings are lower at the centre when the circulation is anticlockwise, and higher when it is clockwise, and this is how the names originated. This is reversed in the Southern Hemisphere, as the effect is created by the rotation of the Earth - the deflection of the air is known as the coreolis effect.
2016-05-25 01:31:03 · answer #3 · answered by gladis 3 · 0⤊ 0⤋
no idea
2007-10-23 01:52:45 · answer #4 · answered by boxer 3 · 0⤊ 0⤋