World’s Physical Geography

Model Answer

Air masses are large volumes of air that have a uniform temperature and moisture content, extending from the Earth’s surface to the lower stratosphere. They typically cover vast areas, sometimes thousands of kilometers, and can influence weather patterns over large regions. The characteristics of an air mass are determined by the temperature and humidity, which are shaped by the region where the air mass originates.

Types of Air Masses

1. Maritime Tropical (mT): Warm and humid, originating over tropical oceans.
2. Maritime Polar (mP): Cold and humid, forming over the oceans in polar latitudes.
3. Continental Polar (CP): Cold and dry, originating from land in the polar regions.
4. Tropical (CT): Hot and dry, originating over land in tropical regions.
5. Continental Arctic (CA): Extremely cold and dry, originating from the North Pole.
6. Continental Antarctic (CAA): Extremely cold and dry, originating from the South Pole.

Significance of Air Masses

Air masses influence local weather by carrying the temperature and moisture characteristics from their source regions to new areas. Fronts are formed when air masses meet, leading to significant changes in weather patterns. Air masses also modify their weather based on the surface they move over. For example, a continental polar air mass can pick up moisture from warmer waters.

Air masses contribute to precipitation, drought, and variations in weather. For instance, hot and dry air masses may lead to drought conditions, while moist air masses can cause rain and thunderstorms. Thus, air masses play a crucial role in determining the climate and weather of different regions.

Model Answer

Weathering

Weathering is the process through which rocks break down into smaller fragments due to mechanical disintegration and chemical decomposition. This process is driven by weather and climate elements and plays a crucial role in soil formation, landform creation, and the concentration of valuable ores like iron, copper, and manganese.

Types of Weathering Processes

Chemical Weathering

• Carbonation: Carbon dioxide reacts with water to form carbonic acid, which dissolves rocks like limestone (source: geology studies).
• Hydration: Minerals absorb water, expand, and eventually fracture the rock.
• Oxidation and Reduction: Iron-rich rocks oxidize in the presence of oxygen, and reduction occurs when oxygen is absent, typically below the water table.

Physical Weathering

• Unloading and Expansion: Removal of overlying rock leads to pressure release, causing rock layers to crack.
• Freeze-Thaw (Frost Wedging): Repeated freezing and thawing of water in cracks weaken rocks.
• Salt Weathering: Salts expand in heat, causing rock disintegration.

Biological Weathering

• Burrowing and Wedging: Animals like earthworms expose new rock surfaces to weathering.
• Plant Roots: Roots exert pressure that breaks apart rocks.

These processes often interact, with one type dominating based on local environmental conditions.

Model Answer

Temperature Inversion

Temperature inversion refers to a reversal of the normal temperature gradient in the troposphere, where a layer of cool air at the surface is overlain by warmer air. Under normal conditions, temperature decreases with height, but during an inversion, it increases with height (Source: Meteorology Textbooks). This phenomenon occurs under calm, clear night conditions that prevent vertical mixing of air.

Types of Temperature Inversions

1. Frontal or Cyclonic Inversion: Occurs when a warm front rises over a cold front, leading to a sloped inversion layer (Source: Weather Patterns).
2. Valley Inversion: Happens in valleys or mountain regions, where cool air settles at the bottom due to rapid surface cooling, while the air above remains warmer (Source: Geographic Studies).
3. Surface Inversion: Develops during clear, calm nights when the ground cools quickly, chilling the air near the surface and creating fog (Source: Climatology Reports).
4. Subsidence Inversion: Results when air masses descend, compress and warm, creating a stable layer that prevents upward air movement (Source: Atmospheric Dynamics).

Implications of Temperature Inversion

Temperature inversion can significantly affect weather patterns by causing poor air quality, reduced visibility due to trapped pollutants, and increased fog. It can also lead to atmospheric stability, preventing the normal vertical movement of air, which suppresses cloud formation and precipitation. Inversions can result in frost damage to vegetation in valleys, where cold air settles while higher altitudes remain warmer (Source: Agricultural Reports).