Atmospheric Circulation and Climate Processes

El Nino is a warm ocean current that temporarily replaces the cold Peruvian current, raising water temperatures by about 10°C. This warm current DECREASES plankton population since planktons thrive in cold nutrient-rich water. Therefore, statement D is NOT true because El Nino reduces planktons rather than increasing them.

The described climate characteristics - warm summers (20°C), very cold winters (-15°C), low annual rainfall (15cm) concentrated in spring/early summer, and coniferous vegetation - match the Siberian type environment. This is a continental climate with extreme seasonal temperature variations and limited precipitation, typical of taiga regions.

Desert plants adapt to conserve water by reducing leaf surface area. Hard/waxy leaves prevent transpiration, and thorns (modified leaves) reduce surface area and deter herbivores.

Albedo is the measure of diffuse reflection of solar radiation out of the total solar radiation received by an astronomical body. Fresh snow has the highest albedo (around 80-95%), forests have low albedo, and water has very low albedo, giving the descending order of snow, forest, water.

The normal lapse rate in the troposphere is approximately 6.5°C per 1000 meters, which simplifies to about 1°C for every 154-165 meters. Option B (156m) is the closest approximation among the given choices and represents the standard value used in meteorology.

The equatorial region is often characterized by dense forests and difficult terrain, which can hinder infrastructure development, but it is not universally an area of 'sluggish development' in economic terms. The reason given, 'extreme climatic conditions', is true as it is hot and humid, but it is not the primary or sole explanation for development levels.

The polar night jet stream occurs in winter above the tropopause in the stratosphere. It forms due to the extremely steep temperature gradient between the cold polar region (in polar darkness) and warmer mid-latitudes. This is distinct from the tropospheric jet streams and is specifically associated with winter stratospheric circulation.

The westerlies do blow between 40° to 60° latitudes in both hemispheres. Reason R explains this correctly - air flows from subtropical high-pressure belts (around 30°) toward subpolar low-pressure zones (around 60°), creating the mid-latitude westerly wind system. The Coriolis effect deflects this flow to the west, creating westerlies.

Wind velocity varies spatially due to pressure differences in the atmosphere. The barometric gradient (rate of pressure change over distance) directly controls wind speed - steeper pressure gradients produce stronger winds as air flows from high to low pressure areas. This is why isobars on weather maps are closely spaced where winds are strong.

Fohn and Chinook are both warm, dry downslope winds that occur on the leeward sides of mountain ranges. Fohn winds are experienced in the valleys of the northern Alps in Switzerland, while Chinook winds occur on the eastern slopes of the Rocky Mountains in North America. Both are caused by air descending and warming after crossing mountain barriers.

Hot deserts experience the maximum daily and annual range of temperature because they have minimal cloud cover and sparse vegetation. During the day, intense solar radiation causes rapid heating, while at night, the lack of cloud cover and low humidity allow rapid heat loss through terrestrial radiation. This creates extreme diurnal and annual temperature variations.

Evaporation involves gain of heat (absorbing latent heat) as water changes from liquid to vapor. Condensation is the transformation of water vapor into water (releasing latent heat). Precipitation is the release of moisture from clouds. Isolation refers to incoming solar radiation reaching Earth's surface. The correct matching is A-4 (Evaporation gains heat), B-3 (Condensation transforms vapor to water), C-1 (Precipitation releases moisture), D-5 (Isolation is incoming solar radiation).

Superimposed drainage occurs when a river system is forced to flow over newer geological structures, characteristic of Peninsular India's ancient rivers adjusting to tectonic changes. Antecedent drainage maintains its course across rising mountain ranges, typical of Himalayan region rivers that predate mountain uplift. Jet streams occur in upper atmospheric zones (5). Inland drainage is found in desert areas (3) where rivers don't reach the sea. The correct matching is A-1, B-2, C-5, D-3.

Tundra climate occurs at very high latitudes (2) where tree growth is limited by permafrost. Monsoon climate covers large areas of the tropics (3) with seasonal wind shifts. Mediterranean sub-tropical climate occurs on continental western margins between 30° to 40° N and S (1) with dry summers. Equatorial climate occurs in continental interiors along the equator (4) with consistently high temperatures and rainfall. The correct matching is A-2, B-3, C-1, D-4.

The collision-coalescence process is applicable to clouds which extend beyond the freezing level (warm clouds). In this process, larger water droplets fall faster and collide with smaller droplets, merging to form even larger drops that eventually fall as rain. This process operates primarily in the warm portion of clouds above the freezing level, unlike the ice crystal process that dominates in colder clouds.

Both statements are true and the Reason correctly explains the Assertion. Seas near the equator do receive rainfall throughout the year because high temperatures cause continuous evaporation, and high humidity provides abundant moisture. When this warm, moist air rises (convection), it cools and condenses, producing afternoon convectional rainfall nearly every day. This is the mechanism behind the observed pattern.