Test: Physical Geography - 1 - UPSC MCQ

The favorable weather elements for dew include clear skies, light wind, decent soil moisture. Clear skies allow for the maximum release of longwave radiation to space.
Cloudy skies will reflect and absorb while remitting longwave radiation back to the surface and that prevents as much cooling from occurring. So B is the most appropriate reason.

As per the NASA webpage:

• Large amounts of methane are frozen in Arctic tundra soils and in marine sediments including gas hydrates. As Earth's climate warms, that methane is vulnerable to possible release into the atmosphere, where it can add to global warming. So 1 and 2 are correct.
• In Methane Cycle, every molecule of methane that goes into the atmosphere remains there for 8 years until it is removed by oxidation into carbon dioxide (CO₂) and water (H₂O). So, 3 is also correct.

• On 21st June, the Northern Hemisphere is tilted towards the sun. The rays of the sun fall directly on the Tropic of Cancer. So, (c) and (d) are wrong.
• Places beyond the Arctic Circle experience continuous daylight for about six months. So (a) is correct.

1. Correct.
2. Incorrect.
3. Correct.

Explanation:

1. The Earth's magnetic field has indeed reversed multiple times throughout its history, with reversals occurring approximately every few hundred thousand years. These reversals are known as geomagnetic reversals and are caused by changes in the flow of molten iron in the Earth's outer core.

2. This statement is incorrect. When the Earth was formed around 4.6 billion years ago, its atmosphere was primarily composed of hydrogen and helium. Oxygen levels were extremely low, and carbon dioxide was present. The development of photosynthesizing organisms helped increase Earth's oxygen levels to the current 21%, while carbon dioxide levels have fluctuated over time.

3. This statement is correct. As living organisms, particularly photosynthesizing organisms, began to evolve and proliferate, they significantly impacted the Earth's atmosphere. Through the process of photosynthesis, these organisms converted carbon dioxide and water into oxygen and glucose, gradually increasing the levels of oxygen in the atmosphere. This made the environment more suitable for the development of aerobic organisms, which rely on oxygen to survive.

Studies have shown that increased concentrations of carbon dioxide increase photosynthesis, spurring plant growth...Results showed that carbon dioxide fertilization explains 70 percent of the greening effect [NASA 2016]

Sand Mining wrecks the intertidal area and creates the imminent danger of saline water ingress into fresh water." Meaning salinity will increase, so statement 1 is wrong, by elimination we've answer (b) 2 and 3 only. In this question, first statement is wrong, and you've to identify right statements. So in real exam stress, some students may have made error of reading / ticking, and they'd have ticked the wrong option A: only 1. (you're right that it's wrong statement, but you're not asked to tick the wrong one.) So, be mindful of ticking in OMR.

The process of decay, added by bacterial action, transforms organic matter into humus. Humus enhances water retention capacity of the soil. So, 1 is wrong. By elimination we are left with Answer (b): 3 only.

Barren Island volcano became active again in March, 1991. A second phase of eruptions started in 1995. So it means third statement is wrong, by elimination, we've the answer (a) only 1.

• The Hindu: Indian Ocean Dipole (IOD) is an event which the western Indian Ocean becomes alternately warmer and then colder than the eastern part of the Indian ocean. So first statement is wrong.
• A positive IOD leads to greater monsoon rainfall and more active (above normal rainfall) monsoon
  days while negative IOD leads to less rainfall and more monsoon break days (no rainfall). So
  yes, IOD can influence El Nino's impact on Monsoon. So second statement is right.

The Brahmaputra enters India in the state of Arunachal Pradesh from its original source Tibet, and is joined by the Dibang River and the Lohit River at the head of the Assam Valley. It is joined in Sonitpur by the Kameng River (or Jia Bhoreli).
Brahmaputra’s main left bank tributaries, viz., Dibang or Sikang and Lohit. The important right bank tributaries are the Subansiri, Kameng, Manas and Sankosh. Therefore, all 3 correct.

Convergence of the two equatorial currents

Explanation:

The Equatorial Counter Current is an eastward-flowing, wind-driven current that is found in the Atlantic, Indian, and Pacific Oceans. It flows between the North Equatorial Current and the South Equatorial Current. The Earth's rotation does affect ocean currents, but it is not the primary reason for the eastward flow of the Equatorial Counter Current.

The convergence of the two equatorial currents (North Equatorial Current and South Equatorial Current) is the main factor that explains the eastward flow of the Equatorial Counter Current. These two currents are driven by the trade winds, which blow from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere. The trade winds push water masses towards the equator, where they converge and create the eastward-flowing Equatorial Counter Current. This current helps to redistribute heat and maintain the overall circulation of the global ocean system.

The difference in salinity of water and the occurrence of the belt of calm near the equator (also known as the Intertropical Convergence Zone) do have effects on ocean currents, but they are not the primary factors that explain the eastward flow of the Equatorial Counter Current.

Reasons for the lack of cyclone formation in the South Atlantic

• Sea surface temperatures run a shade cooler than the one ideal for tropical cyclone formation.
• Climatologically high values of vertical wind shear across that basin throughout the year even in summer.
• Vorticity: Lack of pre-existing centres of rotation in the area.
• Absence of tropical waves.
• The Intertropical Convergence Zone (ITZC), which shifts toward the north in northern summer and toward the south in the southern summer, usually stays at or north of the equator.
• The tropospheric vertical wind shear is much too strong and there is typically no inter-tropical convergence zone (ITCZ) over the ocean.
• Without an ITCZ to provide synoptic vorticity and convergence resulting in large-scale spin and thunderstorm activity as well as having strong wind shear, it becomes very difficult to generate tropical cyclones.
• ITCZ stays at or near the equator and does not shift southward over the south Atlantic or South Pacific region. Therefore, these regions do not have the ITCZ over them which is a major cause of the lack of cyclones.
• Lower sea temperatures are also a reason.

The passage points out equatorial region.

Tides are the rise and fall of sea levels caused by the combined effects of gravitational forces exerted by the Moon, Sun, and rotation of the Earth.

The Westerlies are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes and tend towards the poles and steer extra tropical cyclones in this general manner. The moist air masses that cause winter rains in North-Western region of India are part of westerlies.

Continental Drift has affected the evolution of animals, the world's geographical positions and the world's climates. The split of the original super land mass Pangea into Gondwanaland and the laurasia created new geographical/ climatic regions. The rearrangement and displacement of huge landmasses has helped create the diversity which we see in modern day species.
The final stages of evolution of Genus Homo occurs in the last 3 glacial cycles.

The central Asian steppes run through Kazakhstan, Turkmenistan, Uzbekistan and Mongolia. The climate here is harsh with dust storms, little to no rainfall and temperature ranging from – 4 to 50 degree Celsius.

The first statement is correct. One major factor affecting the distribution of the temperature of Earth is distribution of Land and Oceans. Since there  is  more land  in  Northern Hemisphere and more waters in Southern hemisphere and there is a big difference between the specific heat of land and water; the loss of heat from the continents is bigger than the oceans.
The continents get heated faster and get cooled faster in comparison to the oceans. This is the reason that the temperatures of the Oceans are moderate while that of continents is extreme. The moderating effect on temperature of the land due to proximity of the seas is called Maritime influence. The increasing effect on temperature of the land at interior of the continents is called Continental Influence.

The canopy is the primary layer of the forest forming a roof over the two remaining layers. The densest of the biodiversity is found here along with a large variety of epiphytes.

The mixing of warm and cold current in the region where planktons are found, is food for fishes. The temperature is just right for them to survive.
The temperature is just right for the growth of fish food called planktons.