Daily Quiz: UPSC Prelims Marathon – February 2, 2018

Factors affecting climate:

Distance from the sea (Continentality): The sea affects the climate of a place. Coastal areas are cooler and wetter than inland areas. Clouds form when warm air from inland areas meets cool air from the sea.  The centre of continents are subject to a large range of temperatures.  In the summer, temperatures can be very hot and dry as moisture from the sea evaporates before it reaches the centre of the land mass.

Direction of prevailing winds: Winds that blow from the sea often bring rain to the coast and dry weather to inland areas.

The shape of the land (‘relief’): Climate can be affected by mountains. Mountains receive more rainfall than low lying areas because as air is forced over the higher ground it cools, causing moist air to condense and fall out as rainfall. The higher the place is above sea level the colder it will be.  This happens because as altitude increases, air becomes thinner and is less able to absorb and retain heat. That is why you may see snow on the top of mountains all year round.

Statement 1 and 2 are correct:

El Niño is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean. El Nino is the “warm phase” of a larger phenomenon called the El Nino-Southern Oscillation (ENSO).

El Niño has an impact on ocean temperatures, the speed and strength of ocean currents, the health of coastal fisheries, and local weather from Australia to South America and beyond. El Niño events occur irregularly at two- to seven-year intervals. However, El Niño is not a regular cycle, or predictable in the sense that ocean tides are.

During an El Niño event, westward-blowing trade winds weaken along the Equator. These changes in air pressure and wind speed cause warm surface water to move eastward along the Equator, from the western Pacific to the coast of northern South America.

These warm surface waters deepen the thermocline, the level of ocean depth that separates warm surface water from the colder water below. During an El Niño event, the thermocline can dip as far as 152 meters (500 feet).

This thick layer of warm water does not allow normal upwelling to occur. Without an upwelling of nutrient-rich cold water, the euphotic zone of the eastern Pacific can no longer support its normally productive coastal ecosystem. Fish populations die or migrate. El Niño has a devastating impact on Ecuadorian and Peruvian economies.

Statement 3 and 4 are incorrect:

El Niño also produces widespread and sometimes severe changes in the climate. Convection above warmer surface waters bring increased precipitation. Rainfall increases drastically in Ecuador and northern Peru, contributing to coastal flooding and erosion. Rains and floods may destroy homes, schools, hospitals, and businesses. They also limit transportation and destroy crops.

As El Niño brings rain to South America, it brings droughts to Indonesia and Australia. These droughts threaten the region’s water supplies, as reservoirs dry and rivers carry less water. Agriculture, which depends on water for irrigation, is threatened.

Some of the major Features of Equatorial Climate:

The most outstanding feature of the equatorial climate is its great uniformity of temperature throughout the year. The mean monthly temperatures are always around 80°F. with very little variation. There is no winter. Cloudiness and heavy precipitation help to moderate the daily temperature, so that even at the equator itself, the climate is not unbearable.

Precipitation is heavy, between 60 inches and 100 inches, and well distributed throughout the year. There is no month without rain, and a distinct dry season like those of the Savanna or the Tropical Monsoon Climates, is absent.

Instead, there are two periods of maximum rainfall, in April and October as shown in Fig. 122 (a) and 122 (b), which occur shortly after the equinoxes. Least rain falls at the June and December solstices.

The double rainfall peaks coinciding with the equinoxes are a characteristic feature of equatorial climates not found in any other type of climate.

High temperature and abundant rainfall in the equatorial regions support a luxuriant type of vegetation-the tropical rain forest. In the Amazon lowlands, the forest is so dense and so complete in its vegetational extravagance that a special term ‘selvas’ is used.

Unlike the temperate regions, the growing season here is all the year round-seeding, flowering, fruiting and decaying do not take place in a seasonal pattern, so some trees may be in flower while others only a few yards away may be bearing fruit. There is neither drought nor cold to check growth in any part of the year.

Source:

A tropical marine climate is usually experienced by islands and coastal areas 10° to 20° north or south of the equator.

The ocean is the main influence in creating the tropical marine climate.

There are two main seasons: the wet season and the dry season. The annual rainfall is 1000 to over 1500 mm. The temperature ranges from 20°C to 35°C.

The trade winds blow all year round and are moist, as they pass over warm seas.

All the above statements are correct:

1. The basic cause of Monsoon climates is the difference in the rate of heating and cooling of land and sea. In the summer, when the sun is overhead at the Tropic of Cancer, the great landmasses of northern hemisphere are heated. Central Asia, backed by lofty Himalayan Ranges is more than 15*F. hotter than its normal temperature and a region of intense low pressure is set up. The seas which warm up much slower, remain comparatively cool. At the same time the southern hemisphere experiences winter and a region of high pressure is set up in the continental interior of Australia winds blow outwards as the South East Monsoon, to Java, and after crossing the equator are drawn towards the continental low pressure area reaching the Indian subcontinent as the South West Monsoon. In the Winter the conditions are reversed.
2. The monsoonal vegetation is dependent on the amount of summer rainfall thus the vegetation is most varied ranging from forests to thickests, and from savanna to scrubland.
3. Shifting cultivation is the most primitive form of farming widely practised in the monsoonal type of vegetation. Shifting cultivation is so widely practised amongst indigenous peoples that different local names are used in different countries. For Example: ladang in Malaysia, taungya in Burma, tamrai in Thailand, caingin in Phillipines, humah in Java, Chena I Sri lanka, milpa in Africa and central America.

Statements 1 and 3 are correct:

This type of climate is experienced along the eastern coasts of tropical lands, receiving steady rainfall from the Trade Winds all the time. The rainfall is both orographic where the moist trades meet upland masses in eastern Brazil, and convectional due to intense heating during the day and in summer. Its tendency is towards a summer maximum as in monsoon lands, but without any distinct dry period. The range of temperature is typical of the tropical latitudes with a maximum of 82*F. in January and a minimum of 70’1′. in July -a range of 12*F, for the year.

Statement 2 is incorrect:

Due to the steady influence of the trades, the Tropical ‘Marine Climate is more favourable for habitation, but it is prone to severe tropical cyclones, hurricanes or typhoons.