Climate & Climatic Region Drill Test - 9

In India, the climate and associated weather conditions are not governed by southern cyclonic disturbances. It is the western cyclonic disturbances that govern the climate and associated weather conditions in India.

This is the correct option. Isotherm is an imaginary line drawn on the map joining all the places having the same temperature above sea level. Isobar is an imaginary line drawn on the map joining all the places having the same pressure above sea level. Isohyet is an imaginary line drawn on the map joining all the places having the same amount of rainfall.

During April and May, when the sun shines vertically over the Tropic of Cancer, the large landmass in the north of Indian ocean gets intensely heated. This causes the formation of an intense low pressure in the northwestern part of the subcontinent. Towards the end of summer, there are pre-monsoon showers which are a common phenomena in Kerala and coastal areas of Karnataka. Locally, they are known as mango showers since they help in the early ripening of mangoes.

In Andaman and Nicobar Islands and Kerala there is hardly any difference in day and night temperatures. In Rajasthan, the day temperature rises and the night temperature drops. The sudden increase in temperatures over the land of kings can be accredited to the formation of an induced cyclonic circulation in the wake of an active Western Disturbance.

The distance from the desert is not one of the controls of the climate of a place. The distance from the sea is a control. As the distance from the sea increases, its moderating influence decreases.

The difference between pressures over Tahiti and Darwin is computed to predict the intensity of the monsoons.
Tahiti (18°S/149°W) lies in the Pacific Ocean and Darwin (12°30'S/131°E) lies in northern Australia. If the pressure differences are negative, it means a below average and late monsoon.

El Niño is the warm phase of the El Niño–Southern Oscillation and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific, including the area off the Pacific coast of South America. The presence of El Nino does not lead to strengthening of the trade winds in the region. But, it leads to increase in sea-surface temperatures in the region. The presence of El Nino does not lead to decrease in sea-surface temperatures in the region.

Monsoon winds are fluctuating in nature due to different atmospheric pressure. The winds encounter various atmospheric conditions on their way. The changes in pressure over the southern oceans also affect the monsoons when they cross over tropical seas. This makes them pulsating in nature and not steady. A broad trough of low pressure in equatorial latitudes is known as ITCZ (Inter-Tropical Convergence Zone). It is a zone of convergence at the thermal equator. It is the region where the trade winds meet. Because Earth rotates on its axis, circulating air is deflected towards the right in the Northern Hemisphere and towards the left in the Southern Hemisphere. This deflection is called the Coriolis effect.

Summer is the hottest of the four temperate seasons, falling after spring and before autumn. At or around the summer solstice (about 3 days before Midsummer Day), the earliest sunrise and latest sunset occurs, the days are longest and the nights are shortest, with day length decreasing as the season progresses after the solstice. The date of the beginning of summer varies according to climate, tradition, and culture. When it is summer in the Northern Hemisphere, it is winter in the Southern Hemisphere, and vice versa. The northern parts of the country experience rising temperature and falling air pressure in the summer months.

Dust storms commonly occur in the Indo-Gangetic Plains (IGP) — the fertile plains in northern India that stretch all the way to the east — from March to May, the pre-monsoon season.

Mawsynram village is situated in East Khasi Hills district of Meghalaya. It is the wettest place on Earth, getting an average rainfall of 1187 cm per annum. Mawsynram is a town in the East Khasi Hills district of Meghalaya state in northeastern India, 60.9 kilometres from Shillong. Mawsynram receives the highest rainfall in India.

These tropical cyclones are often very destructive. The thickly populated deltas of the Godavari, the Krishna and the Kaveri are frequently struck by cyclones, which cause great damage to life and property. Sometimes, these cyclones arrive at the coasts of Odisha, W. Bengal and Bangladesh. The bulk of rainfall of the Coromandel coast is derived from depression and cyclones.

(i) The rainfall distribution is highly unequal in our country. Parts of western coast and northeastern India receive over about 400 cm of rainfall annually.
(ii) However, it is less than 60 cm in Western Rajasthan and adjoining parts of Gujarat, Haryana and Punjab. Rainfall is equally low in the interior of the Deccan plateau, and east of the Sahyadris.
(iii) A third area of low precipitation is around Leh in Jammu and Kashmir.
(iv)The rest of the country receives moderate rainfall. Snowfall occurs in the Himalayan region.

The temperature begins to fall rapidly in northern India by the second half of October. The low-pressure conditions over northwestern India move to the Bay of Bengal by early November. This shift leads to cyclonic depressions over the Andaman Sea. These cyclones usually cross the eastern coasts of India and cause heavy and widespread rain. These cyclones may also arrive at the Coasts of Orissa, West Bengal and Bangladesh. These cyclones contribute to the bulk of the rainfall of the Coromandel Coast.

During October-November, with the apparent movement of the sun towards the south, the monsoon trough or the low-pressure trough over the northern plains becomes weaker. Replaced by a high-pressure system. The south-west monsoon winds weaken and start withdrawing gradually. Owing to the conditions of high temperature and humidity, the weather becomes rather oppressive during the day. This is commonly known as 'October heat'. In the second half of October, the mercury begins to fall rapidly in northern India.

 

The low-pressure conditions over northwestern India get transferred to the Bay of Bengal by early November causing cyclonic depressions originating over the Andaman Sea.