Tag: variations in atmospheric pressure

At a high altitude pressure is low as at higher elevations, there are fewer air molecules above a given surface than a similar surface at lower levels.

Due to the intense heating from sun rays around the equator, the air in this region gets hot and hence ascends upwards, thus creating a low pressure in the region. Hence it is the equatorial low-pressure belt and is also called doldrums as it is the region of extreme calmness, not as much as a breeze.

Although air is well mixed throughout the atmosphere, the atmosphere itself is not physically uniform but has significant variations in temperature and pressure with altitude, which define a number of atmospheric layers i.e. when lower layers have atmospheric pressure and higher ones have low atmospheric pressures due to the altitude.

Air pressure increases when air descends. Lower pressure at higher altitudes cause the temperature to be colder on top of a mountain than at sea level. As air rises, the pressure decreases. It is this lower pressure at higher altitudes that causes the temperature to be colder on top of a mountain than at sea level.

The factors which affects in the distribution oof atmospheric pressure are, altitude, temperature and rotation of the earth. Atmospheric pressure decreases with increaseing altitude. Regional variation of pressure are produced by temperature. Movement of wind are also responsible for pressure channge, prevailing wind systems are caused by rotation of the earth.

The weight of water vapor per unit weight of air is called Specific humidity. It is usually expressed as grams of vapor per kilogram of air. The rate of evaporation of water from any surface is directly proportional to the specific humidity, the difference between the surface and the adjoining air. It is an extremely useful quantity in meteorology. Specific humidity does not change with temperature and pressure.

Wind
Air moves from the high-pressure areas to low-pressure areas, creating the wind.
Now with the difference in speeds of traveling wind, it may be called as the storm, hurricane, etc.

Low temperature causes air to contract and higher temperature causes air to expand.

As air warms up, the molecules in the air become more active and they use up more individual space. This leads to a rise in the air pressure. Similarly, when the air cools down the molecules remain compact, leading to a decrease in air pressure.

As we go up the pressure decreases with altitude.

This is because at higher altitudes number of air molecules present are low when compared to those that are present in the lower atmosphere.

Moreover gravitational pull which is responsible for atmospheric pressure is low on the molecules that are away from its surface than those that are closer to it.