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has a hot climate and is influenced by the monsoon the more the lid is pressed
winds. in. In an aneroid barometer,
the pressure on the lid is
Elements of Weather
shown by a needle on a dial.
We will discuss here about some elements of the
Changes in air pressure
weather.
affect the weather. A rapid
Air Pressure drop in atmospheric
Air pressure is measured by an instrument called pressure marks the arrival Aneroid Barometer
barometer. Air has weight which presses down on the of a low-pressure system. Low-pressure systems are
Earth. The weight exerted by a column of air on the associated with cloudy, rainy or windy weather. A
surface of the Earth is known as air pressure. rapid increase in atmospheric pressure pushes that
cloudy and rainy weather out, clearing the skies and
Wow Fact bringing in cool, dry air.
Air pressure decreases with increasing
altitude. It is higher at sea level and gets Wow Fact
lower with increase in altitude. At sea level,
2
air pressure is nearly 1.05 kg/cm . China produces most of the wind energy in
the world. The United States closely follows
as the second largest wind energy producer.
Simple Mercury Barometer
Winds
It comprises of a tube with one end open and placed in
mercury. As air has weight, it exerts pressure on the Winds are the horizontal movements of air caused by
mercury making it rise in the tube. Normal temperature changes, which, in turn, cause changes in
atmospheric pressure at sea level is 760 mm or 30 air pressure. Air pressure increases when
inches of mercury. When expressed in millibars, it is temperatures are low and decreases when
1,013 millibars. If the mercury rises above this point, temperatures are high. Winds blow from regions of
we say that the air pressure is high but when it falls low temperature and high pressure towards regions of
below this point, the pressure is said to be low. high temperature and low pressure. Coastal regions
enjoy cool sea breeze as air blows towards the hot
land during the day. At night, the cooler land breeze
blows out towards the sea. There are similar air flow
patterns along lake sides.
While studying the weather, it is necessary to learn
about the direction and speed of the winds. A wind is
described or named after the direction from which it
comes. A south wind blows from the south towards
the north. An east wind blows from the east towards
the west. Wind direction is determined by an
instrument called wind vane. Wind speed is measured
with an anemometer.
Mercury Barometer
Aneroid Barometer
It is made of a thin metal drum from which air has
been removed. The pressure of the outside air pushes
the lid of the drum inward. The higher the air pressure,
Wind vane Anemometer
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