Test: Climatology - 1 - UPSC MCQ

• Rotation of Earth does cause wind movements; change of day and night; distribution of heat on Earth etc. However, it does not explain several other phenomena such as seasons on Earth; extreme heat and cold in Poles etc.

• Sun’s energy causes all these and is ultimately responsible for life and activity on Earth, which also subsumes weather phenomena.

• Earth’s hydrological cycle is only partly responsible for the weather. For example, rainfall patterns, movements of ocean water etc.

• The organic compounds are the amino acids, nucleic acids, proteins, vitamins and pigments.

• Generally, nitrogen is usable only after it is fixed. 90% of fixed nitrogen is biological.

Only a few types of organisms like certain species of soil bacteria and blue-green algae are capable of utilising it directly in its gaseous form.

• Scattering of sunlight by aerosols can reduce visibility (haze) and provide the red colour during sunrises and sunsets. The Earth’s atmosphere was drastically affected by the dispersal of volcanic aerosols.

• Air pollution can lead to an increase in the water flowing through rivers. Pollutants known as aerosols reduce the amount of sunlight reaching the Earth’s atmosphere.

• This reduces evaporation, thus increasing river flow. During the 1980s, river flow in the central European river basin went up by 25% when aerosol levels in the region were at their peak. The study might help in dealing with water shortage, which is likely to be one of the biggest impacts of climate change.

• Elemental oxygen is normally found in the form of a diatomic molecule. However, in the upper reaches of the atmosphere, a molecule containing three atoms of oxygen is found. This would mean a formula of and this is called ozone.

• Unlike the normal diatomic molecule of oxygen, ozone is poisonous and we are lucky that it is not stable nearer to the Earth’s surface. But it performs an essential function where it is found.

• It absorbs harmful radiations from the Sun. This prevents those harmful radiations from reaching the surface of the Earth where they may damage many forms of life.

• Water vapour is a very effective absorber of heat energy in the air, but it does not accumulate in the atmosphere in the same way as the other greenhouse gases. This is down to it having a very short atmospheric lifetime, of the order of hours to days because it is rapidly removed as rain and snow.

• Nitrous oxide is destroyed in the stratosphere and removed from the atmosphere more slowly than methane, persisting for around 114 years.

• Methane is mostly removed from the atmosphere by chemical reaction, persisting for about 12 years. Thus, although methane is a potent greenhouse gas, its effect is relatively short-lived.

• SF6 is included in the Kyoto Protocol because, molecule-for-molecule, it is a powerful greenhouse gas with a long (>1000 years) lifetime in the atmosphere. The signatory nations are thus committed to controlling the rate of its production.

• The early atmosphere, with hydrogen and helium, is supposed to have been stripped off as a result of the solar winds.

• The early atmosphere largely contained water vapour, nitrogen, carbon dioxide, methane, ammonia and very little free oxygen. The process through which the gases were outpoured from the interior is called degassing.

• Finally, the composition of the atmosphere was modified by the living world through the process of photosynthesis.

• It is through the process of differentiation that the Earth forming material got separated into different layers. Starting from the surface to the central parts, we have layers like the crust, mantle, outer core and inner core.

Explanation:

- Statement 1: True. The atmosphere contains more freshwater than all the surface rivers combined due to the vast amount of water vapor it holds, which is part of the water cycle.

- Statement 2: False. Groundwater constitutes a significantly larger volume of freshwater than rivers.

- Statement 3: False. The polar ice caps hold the majority of the Earth's freshwater, more than lakes, rivers, and groundwater combined.

- Statement 4: True. The average ocean salinity is approximately 35 parts per thousand.

Thus, statements 1 and 4 are correct.

• The evolution of the present atmosphere is a three-stage process. During the first stage, the primordial atmosphere disappeared. In the second stage, the evolution of the atmosphere is subsidised by the hot interior of the Earth. In the final stage, the process of photosynthesis in the living world modified the composition of the atmosphere.

• The early atmosphere is believed to have disappeared due to the solar winds. The solar wind affects not only the Earth but also all the terrestrial planets, which were supposed to have lost their primordial atmosphere in the same way.

• With the change of air temperature, the capacity to retain moisture increases or decreases. Warm air can hold more water vapour than cold air.

• A wind vane also called a weather vane or weathercock, is a tool for measuring wind direction and was probably one of the first weather instruments ever used. To determine wind direction, a wind vane spins and points in the direction from which the wind is coming.

• Cirrus clouds are formed at high altitudes (8,000 - 12,000m). They are thin and detached clouds having a feathery appearance. They are always white in colour. These clouds indicate fair Weather.

• Troposphere: The most important layer of the atmosphere with an average height of 13 km. It contains the air that we breathe. Almost all the weather phenomena (rainfall, fog and hailstorm) happen in this layer.

• Stratosphere: Lies above the troposphere, with height extending up to 50 km. This layer is also associated with weather phenomenon. This layer is free from clouds and most ideal for flying aeroplanes. The important feature of this layer is the presence of a layer of ozone gas. We have just learnt its protective action against the harmful effect of the Sun’s rays.

• Mesosphere: Third layer that lies above the stratosphere, with a height that extends up to 80 km. Meteorites bum upon entering from the space.

• Climate refers to the total of weather conditions and variations over a large area For a long period of lime (more than 30 years). Weather refers to the state of the atmosphere over an area at any point in time.

• The elements of weather and climate are the same, i.e. temperature, atmospheric pressure, wind, humidity and precipitation.

• You may have observed that the weather conditions fluctuate very often even within a day. But there is a common pattern over a few weeks or months, i.e. days are cool or hot, windy or calm, cloudy or bright, and wet or dry.

• Based on the generalised monthly atmospheric conditions, the year is divided into seasons such as winter, summer or rainy seasons.

• The location of the thermal equator is not identical to that of the geographic equator. But, this is not due to the Level of insolation received in both hemispheres.

• Land-dominated areas will tend to have a large variation in temperature and a higher average temperature under the same conditions (as compared to a water-dominated area).

• Albedo is the fraction of solar energy (shortwave radiation) reflected from the Earth back into space.

• It is a measure of the reflectivity of the Earth’s surface. Ice, especially with snow on top of it, has a high albedo: most sunlight hitting the surface bounces back towards space. Water is much more absorbent and less reflective.

• So, if there is a lot of water, more solar radiation is absorbed by the ocean than when icc dominates. The soil has the least reflectivity among all options (a) to (d), and thus the most appropriate answer will be Moist Ploughed Soil.

• The Earth is pear-shaped: however, its shape has a bearing on the gravitation forces more, rather than changing the amount of solar energy received at various latitudes.

• If the Earth was vertically flat and not lilted, all places would have received the same solar energy. The dominance of water bodies a (Teels how the solar energy received is distributed, it does not change the amount of energy received per se (barring glaciers that reflect sunlight).

Only a very small fraction (0.1%) is fixed in photosynthesis. More than half is used for plant respiration and the remaining part is temporarily stored or is shifted to other portions of the plant. This energy captured from the Sun further reduces when we pass to higher trophic levels.