Climatology

Concept: The Earth's atmosphere is divided into several layers based on temperature variation with altitude. Each layer has distinct characteristics and plays a different role in protecting and sustaining life on Earth. The main layers of the atmosphere are:

• Troposphere: The lowest layer of the atmosphere where weather phenomena such as clouds, rain, and storms occur. It extends from the Earth's surface up to about 8–18 km depending on latitude.
• Stratosphere: Located above the troposphere and extending roughly from 18 km to about 50 km above the Earth's surface. This layer contains the ozone layer, which absorbs most of the Sun's harmful ultraviolet (UV) radiation.
• Mesosphere: Extends from about 50 km to 85 km above the Earth. It is the layer where most meteors burn up due to friction with atmospheric particles.
• Thermosphere: Located above the mesosphere, extending from about 85 km to several hundred kilometers. This layer contains ionized gases and is where phenomena like auroras occur.

The ozone layer is a region with a high concentration of ozone ( ) molecules. These molecules absorb harmful ultraviolet radiation from the Sun, particularly UV-B and UV-C rays. Without this protective layer, most life on Earth would be severely affected due to increased exposure to harmful radiation.
Step 1: Understanding where ozone concentration is highest.
The ozone layer is primarily concentrated between approximately km and km above the Earth's surface. This altitude range lies within the stratosphere.
Step 2: Eliminating the incorrect options.

• Troposphere: Contains weather systems but does not contain the ozone layer. Small amounts of ozone may exist here but not as a protective layer.
• Mesosphere: Too high above the Earth; ozone concentration is negligible.
• Thermosphere: Extremely thin air with ionized particles; ozone does not accumulate here.

Step 3: Identifying the correct atmospheric layer.
Since the ozone layer exists in the region between – km altitude and this region lies within the stratosphere, the correct answer is:

Concept: The Coriolis Effect refers to the apparent deflection of moving objects such as winds, ocean currents, and projectiles due to the rotation of the Earth. It is a key concept in physical geography and meteorology because it influences global wind systems and ocean circulation. When the Earth rotates from west to east, objects moving over its surface do not travel in a straight line relative to the rotating planet. Instead, their paths appear to curve.

• In the Northern Hemisphere, moving objects are deflected toward the right.
• In the Southern Hemisphere, moving objects are deflected toward the left.

This phenomenon is known as the Coriolis Effect, named after the French scientist Gaspard-Gustave Coriolis.
Step 1: Understanding the cause of the Coriolis Effect.
The Earth rotates on its axis once every 24 hours. Because of this rotation, different parts of the Earth move at different speeds:

• The equator moves faster because it has a larger circumference.
• The polar regions move slower.

When air masses or ocean currents move across the Earth’s surface, the difference in rotational speed causes their paths to deflect.
Step 2: Impact of the Coriolis Effect.
The Coriolis Effect influences many global phenomena, including:

• Global wind systems such as the trade winds and westerlies
• Ocean currents
• Cyclones and anticyclones

For example, cyclones rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere due to the Coriolis Effect.
Step 3: Evaluating the options.

• Earth's revolution around the Sun: Responsible for seasons, not the Coriolis Effect.
• Earth's rotation on its axis: The primary cause of the Coriolis Effect. (Correct)
• Gravitational pull of the Moon: Mainly responsible for tides.
• Uneven heating of the Earth's surface: Causes wind generation but not the Coriolis deflection.

Thus, the correct answer is: