How climate affects weathering. We are going to talk about how climate affects weathering. In school chemistry laboratories, they do experiments to test this, for example using chemicals held in solution in water, then heating it with the bunsen burner to see what happens. Chemical reactions are faster in hot and wet conditions, this tells you about the rates of weathering in different climates. How climate affects weathering. We will talk about four different climates, frost climates, temperate areas, deserts and humid tropical areas. We will need to know what exfoliation means> It is when the outer layer of rock is heated by the sun during the day and causing it to expand at night. Merriman falls in USA, temperate area. Sahara desert in Africa, desert. Map of climates. Alps in France, frost climate. Namib desert in Namibia, desert. Ecuador in South America, humid tropical area.

Frost climates. Himalaya. Found in areas of high mountain ranges as well as close to the North and South poles. The process here is freeze-thaw action. How much weathering happens depend on the number of freeze-thaw cycles, is not so important how severe the frost was. This means in very cold areas the amount of weathering is smaller. Chemical weathering is slow in frost climates, the cold temperature makes the chemical reaction go slower. North Pole. Greenland.

Temperate areas. Valdivia, Chile. Temperate areas have moderate temperatures. Here freeze-thaw action is not important. Exfoliation does not occur. Here what mostly happens is the chemical weathering. Here the rate of weathering is lower than in the Tropics because the temperatures are lower. Columbia river, USA. Eastern Australia, temperate forest.

Deserts Cleopatra’s needle in London-Egypt. Exfoliation is the main weathering process in deserts, this is due to big differences between and minimum and maximum temperatures in a day (Diurnal temperature range). Chemical weathering is extremely slow caused by the lack of moisture. Their weathering rates are the slowest in all the world, we can see it in the archaeological pieces from Egypt from ancient times. They sat that Cleopatra’s Needle in London weathered more in 10 years in the polluted and wet London than in 3500 years in the desert in Egypt. Desert lack soil, so bedrock is often exposed. Caravan desert , China.

Humid tropical areas They have the fastest weathering rates on Earth. Amazon River, South America. They have the fastest weathering rates on Earth. The layer of weathered material lying on top of the bedrock can be up to 40 metres deep, rocks are seen to weather a lot very fast. Thailand, east Asia.