Geography [3 Mark Question Answer]

Pressure: Atmospheric pressure is the pressure that the atmosphere exerts on the surface of the earth because of its weight. There is a close relationship between pressure and temperature — high temperature means low pressure and vice versa. The pressure difference causes horizontal movement of air called wind and vertical movement of air called current, which together cause circulation of air in the atmosphere.

Temperature: When the temperature of a place increases, the air gets heated, expands, and rises. This leads to a decrease in air pressure in the area. When the temperature falls, the air gets cold, contracts, and descends downwards. This leads to an increase in air pressure. Thus, air pressure decreases with an increase in temperature. This is the reason why areas close to the equator generally have low air pressure.

Westerlies blow in the middle latitudes between 30° and 60° latitude and originate from the high-pressure area in the horse latitudes towards the poles. Under the effect of the Coriolis force, they become the South Westerlies in the northern hemisphere and Northern Westerlies in the southern hemisphere.

In regions closer to the equator, the rate of evaporation is very high. Air gets heated because of the high temperature and starts rising in the form of convection currents. As it rises, it expands and cools. The cooling causes condensation, which results in heavy downpours. This rain is accompanied by thunder and lightning and since it mostly occurs around 4 p.m., it is often called the 4 o'clock showers’.

Weather and climate are closely related terms but have different meanings. Weather refers to the atmospheric conditions of a small area for a short period of time, usually 24 hours or one day, while climate is the average of the atmospheric conditions of a larger area, over a long period of time, usually 35 years.