the low pressure belt at equator is
Answers
Answer:
Along the equator lies a belt of low pressure known as the “equatorial low or doldrums”. Low air pressure in equatorial regions is due to the fact that hot air ascends there with gradual decrease in temperatur causing thinness of air on the surface.
Explanation:
The atmosphere is held on the earth by the gravitational pull of the earth. A
column of air exerts weight in terms of pressure on the surface of the earth.
The weight of the column of air at a given place and time is called air pressure
or atmospheric pressure. Atmospheric pressure is measured by an instrument
called barometer. Now a days Fortin’s barometer and Aneroid barometer I
are commonly used for measuring air pressure.
Atmospheric pressure is measured as force per unit area. The unit used for
measuring pressure is called millibar. Its abbreviation is ‘mb’. One millibar
is equal to the force of one gram per square centimetre approximately. A
pressure of 1000 millibars is equal to the weight of 1.053 kilograms per
square centimetre at sea level. It is equal to the weight of a column of mercury
which is 76 centimetre high. The international standard pressure unit is the
“pascal”, a force of one Newton per square meter. In practice atmospheric
pressure is expressed in kilopascals, (one kpa equals 1000 Pa).
Air is a mixture of various gases. It is highly compressible. As it compresses,
its density increases. The higher the density of air, the greater is the air pressure
and vice versa. The mass of air above in the column of air compresses the air
under it hence its lower layers are more dense than the upper layers; As a
result, the lower layers of the atmosphere have higher density, hence, exert
more pressure. Conversely, the higher layers are less compressed and, hence,
they have low density and low pressure. The columnar distribution of
atmospheric pressure is known as vertical distribution of pressure. Air pressure
decreases with increase in altitude but it does not always decrease at the
same rate. Dense components of atmosphere are found in its lowest parts
near the mean sea level. Temperature of the air, amount of water vapour
present in the air and gravitational pull of the earth determine the air pressure
of a given place and at a given time. Since these factors are variable with
change in height, there is a variation in the rate of decrease in air pressure
with increase in altitude. The normal rate of decrease in air pressure is 34
millibars per every 300 metres increase in altitude; (see figure 11.1). The
effects of low pressure are more clearly experienced by the people living in
the hilly areas as compared to those who live in plains. In high mountainous
areas rice takes more time to cook because low pressure reduces the boiling
point of water. Breathing problem such as faintness and nose bleedings are
also faced by many trekkers from outside in such areas because of low pressure
conditions in which the air is thin and it has low amount of oxygen content.
Answer:
Along the equator lies a belt of low pressure known as the “equatorial low or doldrums”. Low air pressure in equatorial regions is due to the fact that hot air ascends there with gradual decrease in temperatur causing thinness of air on the surface.
Explanation: