UPSC Static Quiz – Geography : 5 January 2026

Solution: c)

The geothermal gradient, the amount that the Earth’s temperature increases with depth, indicates heat flowing from the Earth’s warm interior to its surface. At a certain depth, the heat is such that it melts rocks and creates what geologists call ‘magma’.

Magma is lighter than solid rock and hence it rises, collecting in magma chambers. Chambers which have the potential to cause volcanic eruptions are found at a relatively shallow depth. The magma that surfaces on the Earth’s crust is referred to as lava.

Why are some volcanic eruptions explosive and some not?

In simple terms, runny magma makes for less explosive volcanic eruptions that typically are less dangerous. Since the magma is runny, gasses are able to escape, leading to a steady but relatively gentle flow of lava out of the mouth of the volcano. The eruption at Mauna Loa is of this kind. Since the lava flows out at a slow pace, people typically have enough time to move out of the way.

If magma is thick and sticky, it makes it harder for gasses to escape on a consistent basis. This leads to a build-up of pressure until a breaking point is reached. At this time, the gasses escape violently, all at once, causing an explosion. Mount Vesuvius, which obliterated the city of Pompeii, is an example of an explosive volcano.

Solution: b)

Statement 3 is incorrect.

A bomb cyclone is simply a storm that intensifies very rapidly. Bomb cyclones form when air near Earth’s surface rises quickly in the atmosphere, triggering a sudden drop in barometric pressure.

All bomb cyclones are not hurricanes. But sometimes, they can take on characteristics that make them look an awful lot like hurricanes, with very strong winds, heavy precipitation and well-defined eye-like features in the middle.

Hurricanes tend to form in tropical areas and are powered by warm seas. For this reason, they’re most common in summer or early fall, when seawater is warmest.

In contrast, bomb cyclones don’t need balmy ocean waters in order to form. While they sometimes arise over the ocean, they can also appear over land — as was the case with the cyclone that hit the northern Plains in March 2019.

Unlike hurricanes, bomb cyclones arise in mid-latitudes, where fronts of warm and cold air might collide. They rarely strike in summer, when the weather is generally warm across the Northern Hemisphere. Rather, they form between late fall and early spring, when warm tropical air bumps up against frigid Arctic air.

Statement 1 is incorrect: Nuclear fusion involves two light atomic nuclei (such as hydrogen isotopes deuterium and tritium) combining to form a heavier nucleus (helium), releasing immense energy. Fusion does not involve heavy nuclei, unlike nuclear fission.

Statement 2 is correct: Fusion requires extremely high temperatures (above 100 million Kelvin) to overcome the Coulomb barrier (electrostatic repulsion between positively charged nuclei).

Statement 3 is incorrect: Unlike nuclear fission, fusion does not produce long-lived radioactive waste. The primary byproduct of fusion, helium, is non-radioactive, and while fusion reactions involving tritium produce some radioactive materials, their half-life is much shorter than fission waste.

• What is Nuclear Fusion?
  • Nuclear fusion is a process where two light atomic nuclei combine to form a heavier nucleus, releasing immense energy—the same process that powers the Sun and other stars.
• How it works?

• • High Temperature & Plasma Formation: Fusion requires temperatures above 100 million degrees Celsius, creating a plasma state where atoms split into charged particles.
  • Magnetic Confinement: Plasma is confined using strong magnetic fields to prevent contact with reactor walls.
  • Fusion Reaction: Hydrogen isotopes (Deuterium & Tritium) fuse, producing helium and energy in the form of heat.
  • Energy Capture & Conversion: Future reactors aim to use this heat to generate steam, driving turbines to produce electricity.

Difference between Nuclear Fusion and Nuclear Fission:

Solution: c)

• Oyashio current – Pacific Ocean
• Benguela current – South Atlantic Ocean

Solution: a)

Only Statement 1 is correct.

Atmospheric Pressure: force exerted by the weight of the air. Atmospheric pressure is defined as the force per unit area exerted against a surface by the weight of the air molecules above that surface.

Isobars are imaginary lines that connect points of equal atmospheric pressure on a given day. Pressure gradient force is what determines the strength of winds.

Isobars that are widely spaced apart indicate gently blowing winds (pressure gradient force is low).

Isobars that are closely spaced together indicate strong winds (high pressure gradient).

The Coriolis force, caused by the spin of the Earth, determines that moving air masses in the northern hemisphere deflect to the right. It is the opposite in the southern hemisphere.

Solution: c)

Tropical cyclones can relieve drought conditions as they often carry moisture laden winds.

In addition to strong winds and rain, tropical cyclones are capable of generating high waves, damaging storm surge, and tornadoes.

They typically weaken rapidly over and where they are cut off from their primary energy source. For this reason, coastal regions are particularly vulnerable to damage from a tropical cyclone as compared to inland regions.

Heavy rains however, can cause significant flooding inland, and storm surges can produce extensive coastal flooding up to 25 miles from the coastline.

They also carry heat energy away from the tropics and transport it toward temperate latitudes, because they are large wind systems that absorb the frontal conditions of the area they flow in.

Finally, due to the high speed they blow in, they also act as the earth’s filter system by cleansing the air of toxins and pollutants out of the atmosphere.