What do the following indicate in a barometer regarding weather--

1) Gradual fall in the mercury level
2) Sudden fall in the mercury level
3) Gradual rise in the mercury level
4) Sudden rise in the mercury level

Dear Student,
A barometer is a device used to measure atmospheric pressure. The atmospheric pressure is determined in terms of the height of the mercury column. Normally high pressure represents a clear and bright sunny weather while low pressure creates cloudy and rainy weather. Rapid rise represents unsettled weather and gradual rise represents settled weather.
(1) Gradual fall in mercury level of a barometer indicates a gradual decrease in atmospheric pressure which happens due to increase in humidity of the region. It indicates the possibility of rain in the region.
(2). Sudden fall in mercury level of a barometer indicates that a sudden low pressure region is created. This happens when a high pressure is created in its nearby surroundings. This indicates the possibility of storm or tornado in the area.
(3) Gradual rise in mercury column: Gradual rise in mercury column represents a slow increase in atmospheric pressure which happens when moisture gradually gets removed. It represents the case of a pleasant weather.
(4) Sudden rise in mercury level: Sudden rise in mercury level represents creation of a sudden high pressure zone in the region. This suggest that the weather is unsettled and the good weather will not last long.


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Dear student,

Level of mercury in a barometer refers to the atmospheric pressure at that region. If the level of mercury is high, it signifies a high atmospheric pressure and vice versa.

1) Gradual fall in Mercury level:

It signifies that the atmospheric pressure at the region has become low. If the relative humidity in the atmosphere is high, there there is a possibility of rain in that area.

2) Sudden fall in Mercury level:

It signifies that there has been a fast fall in atmospheric pressure over the region. This will pool air from the surrounding regions vigorously and there is a possibility of storm in that area.

3) Gradual rise in Mercury level:

It refers to dry and calm weather.
There is no possibility of rain.


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