subpolar low pressure belt. A band of low pressure located, in the mean, between 50° and 70° latitude. In the Northern Hemisphere, this belt consists of the Aleutian low and the Icelandic low. In the Southern Hemisphere, it is supposed to exist around the periphery of the Antarctic continent.

North American plate,laurasia was the more northern of two supercontinents that formed part of the Pangaea supercontinent around 335 to 175 million years ago.

Environmental degradation is the deterioration of the environment through depletion of resources such as air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife.

The total surface area of the Earth is about 7008510000000000000 . 510 million km (197 million sq mi).

Himalayan rivers get water from snow and rain, whereas Peninsular rivers are fed by rain only. The drainage basin of Himalayan rivers is comparatively larger than the Peninsular rivers. Himalayan rivers water helps in the irrigation of Northern Plains. In contrast, Peninsular rivers irrigate Deccan Plateau.

“Weathering is the breaking down of rocks, soil and minerals as well as wood and artificial materials through contact with the Earth’s atmosphere, biota and waters.

1. Mechanical weathering is the physical breakdown of rocks into smaller and smaller pieces. One of the most common mechanical actions is frost shattering. Another type of mechanical weathering is called salt wedging. Winds, water waves, and rain also have an effect on rocks as they are physical forces that wear away rock particles, particularly over long periods of time.
2. Organic or biological weathering refers to the same thing. It is the disintegration of rocks as a result of the action by living organisms. Trees and other plants can wear away rocks since as they penetrate into the soil and as their roots get bigger Microscopic organisms like algae, moss, lichens and bacteria can grow on the surface of the rocks and produce chemicals that have the potential of breaking down the outer layer of the rock. 
3.  Chemical weathering happens when rocks are worn away by chemical changes. The natural chemical reactions within the rocks change the composition of the rocks over time. Because the chemical processes are gradual and ongoing, the mineralogy of rocks changes over time thus making them wear away, dissolve, and disintegrate. The chemical transformations occur when water and oxygen interacts with minerals within the rocks to create different chemical reactions and compounds through processes such as hydrolysis and oxidation.