school energy&environment

Climate and shape

All processes that shape the Earth’s surface are interlinked and connected to climatic conditions. As a consequence, they are typical of some areas on the Earth. The Mediterranean area, the Polar area, the Tropical area, etc. are named morphoclimatic zones, and are characterized by particular exogenous and climatic factors.
Hot-wet regions
Hot-wet regions are characterized by plenty of water and high temperatures that provoke intense processes of chemical alterations. Their soil is rich in humus and covered by a dense green area that protects the land from river erosion and allows water absorption.
When the mountains consist of granitic rocks, the landscape is gentle and characterized by dome-shaped heights, called inselbergs. Inselbergs can be found isolated or in groups, without soil or vegetation cover. Instead, if the mountains are made of calcareous rocks, they look like pinnacles and towers and characterize the landscapes of Vietnam and Southern China.
Dry regions
There are two different types of dry regions:

• the area of tropical deserts and the savannah, which are characterized by a strong temperature range, lack of rain and absence of vegetation cover. Rock alteration is mainly due to temperature differences, as well as to the presence of dew and wind action. There are hollows, mushroom shapes and tafones, which are typical excavations at the bottom of the rocks created by wind action;
• Antarctica belongs to dry regions because it is covered by perennial ice, humidity is extremely low and snow is the only precipitation. There are shapes created by wind action.

Mild regions
In mild regions, initially rainwater runs in a uniform way on the mountainsides and then it progressively collects along water streams. Distribution and intensity of rains vary according to the regions:

• oceanic regions are characterized by rain falls all year long and the soil has a continuous vegetation cover;
• mediterranean regions are characterised by showers after the dry season. The vegetation cover is not continuous and it is degraded.

Rainwater that runs on the Earth’s surface erodes the soil and forms a series of cracks of different dimensions. In particular:

• if the slope is very steep and is made of clay rocks, the cracks are deep and separated by crests, as the gullies on the Apennines;
• if the land is formed of superficial fragments that are bigger than the ones underneath, the water forms deep cracks around the main rocks. With time passing earth pyramids form, which can reach 20-30 m height, and have the shape of a mushroom with a hat (a big rock) and a stem (made of finer compact material). We can observe earth pyramids in some places on the Alps and near the Lake of Iseo.

Periglacial regions
Rock fragmentation occurs as a consequence of ice action in the areas near the North Pole. Until 30 metres of depth the soil is frozen, but then it swells on the surface forming the permafrost.