Welcome To UnderStand UPSC

Answer : B
Explanation :

• Option A is incorrect : The greenhouse effect is caused by the absorption of infrared radiation (not ultraviolet) by greenhouse gases like carbon dioxide and methane.
• Option B is correct : The Albedo effect refers to the reflection of solar radiation by surfaces like clouds, ice, and snow, which helps cool the Earth by reducing the amount of heat absorbed.
  
• Option C is incorrect: The Coriolis effect is responsible for the deflection of winds and ocean currents, but it is weakest at the equator and strongest at the poles.
  
• Option D is incorrect as : The Hadley Cell is a global atmospheric circulation pattern that transports heat from the equator to the poles, not the other way around.

Answer : D
Explanation : A corona is an atmospheric optical phenomenon that appears as a series of colored rings around the Sun or Moon. It is often observed when thin clouds (like altostratus or cirrostratus) are present in the sky.
The rings are typically bluish on the inside and reddish on the outside, with other colors in between.

• How is a Corona Formed?
  – The corona is caused by the diffraction of light as it passes through tiny water droplets in clouds.
  ○ Diffraction occurs when light waves bend around small obstacles or pass through narrow openings, such as the tiny water droplets in clouds.
  ○ When sunlight or moonlight encounters these droplets, the light waves interfere with each other, creating a pattern of concentric rings of color.

More information :

• Option B describes the formation of halos, not coronas. Halos are caused by the refraction of light through hexagonal ice crystals in cirrus clouds, creating a ring of light around the Sun or Moon.
  
• Option C describes Scattering of light by dust particles causes phenomena like red sunsets or blue skies.

Answer : C
Explanation :
Countries in the Nile River Basin:

1. Burundi - Source of the Kagera River, one of the main tributaries of the Nile.
   
2. Democratic Republic of the Congo (DRC) - Part of the Nile Basin through the Semliki River, which flows into Lake Albert.
   
3. Egypt - The most downstream country, heavily dependent on the Nile for water resources.
   
4. Eritrea - A minor contributor to the Nile Basin, with small tributaries flowing into the Atbara River.
   
5. Ethiopia - Source of the Blue Nile, contributing about 85 percent of the Nile’s water.
   
6. Kenya - Part of the Nile Basin through Lake Victoria, which is a major source of the White Nile.
   
7. Rwanda - Source of the Nyabarongo River, a tributary of the Kagera River.
   
8. South Sudan - The White Nile flows through South Sudan, merging with the Blue Nile in Sudan.
   
9. Sudan - The confluence of the Blue Nile and White Nile occurs in Sudan, making it a key part of the basin.
   
10. Tanzania - Part of the Nile Basin through Lake Victoria, which is shared with Kenya and Uganda.

Uganda - Home to the source of the White Nile at Jinja, where the Nile exits Lake Victoria.

Answer : B
Explanation :

• Statement 1 : Estuaries - Incorrect. Estuaries are formed where rivers meet the sea, but they are distinct from deltas, which are characterized by sediment deposition.
  
• Statement 2: Levees - Correct. Levees are natural embankments formed by the deposition of sediment along the riverbanks in a delta.
  
• Statement 3: Oxbow Lakes - Incorrect. Oxbow lakes are features of meandering rivers, not typically associated with deltas.
  
• Statement 4: Distributaries - Correct. Distributaries are small channels that branch off from the main river in a delta, carrying water and sediment to the sea.

Answer : A
Explanation :

• Statement 1 is correct as The glacial cycle refers to the recurring periods of glaciation (ice ages) and interglacial periods (warmer phases). This cycle is driven by changes in Earth’s orbit, variations in solar radiation, and other factors.
  
• Statement 2 is incorrect as During glaciation, large amounts of water are locked up in glaciers and ice sheets, causing sea levels to fall, not rise. This is because the water is stored on land in the form of ice, rather than being in the oceans.
  
• Statement 3 is incorrect as Interglacial periods are characterized by the retreat of glaciers, but the formation of glacial landforms such as moraines and drumlins occurs during glaciation, not interglacial periods. Moraines are ridges of rock and soil deposited by glaciers, while drumlins are elongated hills formed by glacial erosion. These landforms are created as glaciers move and scour the landscape, and are not typically formed during interglacial periods.