Tag: rivers and their work

The air temperature diminishes as we move from the equator towards the poles because the sun's ray's reach the earth at an angle outside the tropics. So the temperature decreases.

Relief rain occurs when warm air is forced to cool when it rises over a hill or mountain and then condenses. The other name for relief rain is orographic rainfall. The windward side of the mountains receives heavier rainfall in comparison to that of the leeward side (opposite) of the mountain receives little or no rain at all. It always produces a rain shadow effect.

The Intertropical Convergence Zone (ITCZ), known by sailors as the doldrums, is the area encircling the earth near the equator where the northeast and southeast trade winds come together.

The repeated heating and cooling exerts stress on the outer layers of rocks, which can cause their outer layers to peel off in thin sheets. The process of peeling off is also called exfoliation and it is a mechanical process. Over time, sheets of rock break away from the exposed rocks along the fractures, a process known as exfoliation. Exfoliation due to pressure release is also known as "sheeting". Retreat of an overlying glacier can also lead to exfoliation due to pressure release.

Solution is obtained when some substances present in the rocks are directly soluble in water. The soluble substances are removed by the continuous action of water and the rock no longer remains solid and form holes, rills or rough surface and ultimately falls into pieces or decomposes. The action is considerably increased when the water is acidified by the dissolution of organic and inorganic acids.

Biological weathering also means organic weathering. It is the disintegration of rocks as a result of the action by living organisms. Plant and animals have a significant effect on the rocks as they penetrate or burrow into the soil respectively. Biological weathering can work hand in hand with physical weathering by weakening rock or exposing it to the forces of physical or chemical weathering.

Weathering is the breaking down of rocks, soil, and minerals as well as wood and artificial materials through contact with the Earth's atmosphere, waters, and biological organisms. Weathering occurs in situ, that is, in the same place, with little or no movement, and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity and then being transported and deposited in other locations.

Breaking or weakening of rocks is a natural phenomenon. It is called weathering. Weathering can be of three type:-

• Mechanical
• Chemical
• Biological

Mechanical weathering mainly occurs because of the following reasons:-

• Temperature
• Frost
• Crystal growth
• Release of pressure
• Water