Test: Climatology - 2 - UPSC MCQ

• The Equator receives comparatively lesser solar insolation than the tropics despite being at zero latitudes.

• The main reason is the cloudiness of the equator. Generally, at the same latitude, the insolation is moreover the continent than over the oceans, because oceans are cloudier due to greater evaporation.

• Similarly in the equator, evaporation is high, cloudiness is high and rains are frequent. Clouds reflect incoming solar insolation and send it back to space.

• The lapse rate usually is more in summer than winter.

• In hilly areas, a hot day followed by a calm, cloudless night act as a favourable condition for the phenomenon of temperature inversion.

• If the moist air ascends rapidly to the cooler layers of the atmosphere, the water droplets freeze into ice pellets and fall to the earth as hail.

• Climate change-induced global warming, urbanisation, deforestation etc have further increased instances of heatwaves.

• It is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western parts of India. Heatwaves typically occur between March and June, and in some rare cases even extend till July.

• When the actual maximum temperature remains 45°C or more irrespective of normal maximum temperature, heat waves should be declared.

• This is due to greater evaporation. Similarly, in the equator, evaporation is high, cloudiness is high and rains are frequent. Clouds reflect incoming solar insolation and send it back to space.

• Despite the varied terrain and relief, the amount of insolation received by land isn’t affected so significantly as to cause such a difference in the total insolation received by land and seas.

• The annual variation of surface temperature in any ocean depends upon several factors, the most important among which are the annual variations of radiation income and the prevailing winds.

• The annual range over most of the oceans of the world is less than 5-degree celsius. Maximum annual variations in the sea surface temperature occur generally in mid-latitude regions of the oceans.

• The ranges are generally greater close to the land, due to the land effect and are greater in the northern hemispheric oceans. The annual range of surface temperature is much greater in the North Atlantic and North Pacific oceans than in the southern oceans.

• Isotherms are lines joining places having an equal temperature. The impact of latitude on temperature on the map is generally well pronounced because isotherms are generally parallel to latitude.

• Particularly in the Northern Hemisphere, the deviation from this general trend is more evident in January than in July. The land surface area is much larger in the Northern Hemisphere than in the Southern Hemisphere.

• The effects of landmass and ocean currents are therefore very pronounced. In January, the isotherms deviate to the north via the ocean and to the south via the continent.

• On the North Atlantic Ocean, this can be seen. The warm ocean currents, the Gulf Stream and the North Atlantic drift make the North Atlantic Ocean warmer and the isotherms bend northwards. Over the land, the temperature decreases sharply and the isotherms bend southwards in Europe.

• Usually, within the lower atmosphere (the troposphere) the air near the surface of the Earth is warmer than the air above it, largely because the atmosphere is heated from below as solar radiation warms the Earth’s surface, which in turn then warms the layer of the atmosphere directly above it.

• Given the right conditions, the normal vertical temperature gradient is inverted such that the air is colder near the surface of the Earth. This can occur when, for example, a warmer, less-dense air mass moves over a cooler, denser air mass.

• It can also happen in valleys where the cold air slides down the mountain slope and warm air moves up.

• A temperature inversion is a phenomenon where a layer of warm air is formed on top of a layer of cold air, unlike in normal atmospheric conditions.

• Cloud formations, Thunderstorm Prevention, Trapping of smog are some of the notable effects of Temperature inversion.

• Air pressure is defined as the pressure exerted by the weight of air on the Earth’s surface. As we go up the layers of the atmosphere, the pressure falls rapidly.

• The high-pressure region has clear skies and a calm atmosphere. Winds move towards the Low-pressure region.

• When the temperature is high in the area, the air gets heated and rises, which creates a low-pressure area. Cloudy skies and wet weather are due to low pressure.

• In lower temperature areas, the air is cold. It is therefore heavy.

• Heavy air sinks, creating a high-pressure area. High pressure is related to clear and sunny skies.

• The air always moves towards low- pressure areas from high-pressure areas.

• The Intertropical Convergence Zone (ITCZ), known by sailors as the doldrums, is the area encircling the Earth near the equator where the northeast and southeast trade winds come together.

• The ITCZ appears as a band of clouds, usually thunderstorms, that circle the globe near the equator. In the Northern Hemisphere, the trade winds move in a southwestern direction from the northeast, while in the Southern Hemisphere, they move northwestwards from the southeast.

• When the ITCZ is positioned north or south of the equator, these directions change according to the Coriolis effect imparted by the rotation of the Earth. For instance, when the ITCZ is situated north of the equator, the southeast trade wind changes to a southwest wind as it crosses the equator.

• The ITCZ is formed by vertical motion largely appearing as convective activity of thunderstorms driven by solar heating, which effectively draws air in; these are the trade winds.

• There are two polar vortices in the Earth's atmosphere, which overlie the North and South Poles. Each polar vortex is a persistent, large-scale, low-pressure zone that rotates counterclockwise at the North Pole (called a cyclone), and clockwise at the South Pole.

• The bases of the two polar vortices are located in the middle and upper troposphere and extend into the stratosphere. Beneath that lies a large mass of cold, dense arctic air. The vortices weaken and strengthen from year to year. Northern polar vortex's southward shift will bring heavily cold weather in the northern regions.

Justification:

• Coriolis force acts on the fluid water deflecting it like it deflects the wind. This causes rivers to 'meander'.

• It deflects the wind in the right direction in the Northern Hemisphere and to the left in the Southern Hemisphere.

• Jet streams typically cover long distances and can be thousands of miles long. They can be discontinuous and often meander across the atmosphere. The meanders in the jet stream flow slower than the rest of the air and are called Rossby Waves. They move slower because they are caused by the Coriolis Effect and turn west concerning the flow of air they are embedded in.

• It is a circular depression in the surface of a planet, moon, or other solid body in the Solar System. Hence incorrect.

• The Coriolis force is an inertial force (also called a fictitious force) that acts on objects that are in motion relative to a rotating reference frame.

• The rate of change of rotational speed is zero at the equator and increases polewards, being maximum at the poles. Zero Coriolis force does not allow winds to deflect.

• Since the Coriolis force is zero, tropical cyclones rarely form at the equator. The amount of air deflection is directly associated with both the velocity at which the air moves and its latitude.

• The Coriolis force acts perpendicularly on the pressure-gradient force. The pressure- gradient force and an isobar are perpendicular to each other. If the pressure-gradient force is higher, then the velocity of the wind is higher, and the deflection is more in the direction of the wind.

• They result from strong turbulent winds eroding sand, silt and clay particles from arid landscapes and impoverishing their soils. The storms can raise large quantities of particles high into the air. They can travel thousands of kilometres across continents and oceans, entraining other pollutants on the way and depositing particles far from their origin.

• Dust harms both humans and animals. Chronic exposure to fine dust contributes to premature deaths from respiratory and cardiovascular diseases, lung cancer and acute lower respiratory infections.

• The anthropogenic causes of sand and dust storms include deforestation and unsustainable agricultural practices as well as excessive water extraction and the modification of water bodies for irrigation and other purposes.

• It is a warm and dry westerly wind that blows down the Rocky Mountains into the mountains' eastern slopes and the western prairies.

• It is a hot wind that blows in winter and therefore raises the temperature in a short time. This increase in temperature results in the melting of snow, making pasture land available for grazing of animals.

• The chinook, a native word meaning 'snow eater', belongs to a family of winds experienced in many parts of the world where long mountain chains lie more or less at right angles to the prevailing wind.

• The horse latitudes are located at about 30 degrees north and south of the equator.

• It is common in this region of the subtropics for winds to diverge and either flow towards the poles (known as the prevailing westerlies) or towards the equator (known as the trade winds).

• These diverging winds are the result of an area of high pressure, which is characterised by calm winds, sunny skies and little or no precipitation.

• It is a belt around the Earth extending approximately 5 degrees north and south of the equator. Here, the prevailing trade winds of the Northern Hemisphere blow to the southwest and collide with the Southern Hemisphere's driving northeast trade winds.

• Due to intense solar heating near the equator, the warm, moist air is forced up into the atmosphere like a hot air balloon. As the air rises, it cools, causing persistent bands of showers and storms around the Earth's midsection. The rising air mass finally subsides in what is known as the horse latitudes, where the air moves downwards towards Earth's surface.

• Southeast trade winds blow in the Southern Hemisphere. North-east trade winds flow in the Northern Hemisphere.

• The surface air that flows from these subtropical high-pressure belts towards the Equator is deflected towards the west in both hemispheres by the Coriolis effect.

• These winds blow predominantly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere.

• These are downslope winds flowing from high elevations of mountains, plateaus and hills down their slopes to the valleys or plains below.

• A katabatic wind originates from radiational cooling of air atop a plateau, a mountain, glacier or even a hill. Since the density of air is inversely proportional to temperature, the air will flow downwards, warming approximately adiabatically as it descends.

• The temperature of the air depends on the temperature in the source region and the amount of descent.