Climate & Climate Change (AQA A Level Geography)

Characteristics and Distribution

• The tropical monsoon climate is characterised by a distinct hot, wet (monsoon) season and a cooler dry season
• Temperature can average 30°C in the monsoon season and humidity is also very high
• Average rainfall is around 2000mm for the season (south-east UK receives just over 600mm per year) 
• Cyclones (tropical storms) are frequent towards the end of the rainy season
• Determined by the annual movement of the Inter Tropical Convergence Zone (ITCZ) between the Tropics and associated movement of pressure belts and the seasonal reversal of winds associated with this. 
• In south-east Asia, between May and October the ITCZ brings the strongest sun over the continental landmass, heating the land and causing large masses of air to rise in low pressure zones.
• Moist, warm air from the Indian Ocean to the south-west gets sucked in to replace the rising air over the continent and this brings heavy monsoon rainfall
• In November the ITCZ moves south and the process reverses so that cooler, drier air moves from the continent back towards the Indian Ocean
• Occurs mainly on the eastern side of continents in the Tropics from about 5-20°N and S of the Equator

Distribution of Monsoon Rains

Human Activities and Numbers

• Agriculture in monsoon regions relies heavily on the warm wet conditions and this can produce high yields and support large populations
• More than 4 billion people live in the Asian countries that are visited by summer monsoon winds
• Many areas in these countries do not have large irrigation systems but the summer monsoon rainfall fills aquiders and other groundwater stores for the rest of the year
• Rice and tea are some crops that rely on the summer monsoon 
• Dairy farms, which help make India the largest milk producer in the world, also depend on the monsoon rains to feed the cows
• Industry and energy supplies are fed by the monsoon climate system
• In India and Southeast Asia a large amount of electricity in the region is produced by hydroelectric power plants, which are driven by water collected during the monsoons. 
• This electricity helps to power hospitals, schools, and industry and is as vital to the local economy as the crops the rain helps to grow

Characteristics and Distribution

• Polar climates cover 20% of the earth’s surface
• Found in both northern and southern hemispheres above 66° latitude
• Arctic Ocean and the fringes of northern landmasses that make up the Arctic Circle to the north
• Northern Russia, northern Scandinavia, Greenland, Northern Canada
• Continent of Antarctica to the South
• Very low mean annual temperatures in all Polar regions
• Range in the Arctic is from -40°C in winter to up to +10°C in summer
• Even colder in Antarctica with temperatures falling to -80°C in winter
• Precipitation levels less than 100mm per year in all polar regions, making them (polar) deserts
• Tundra refers to areas of permafrost that fringe the ice caps at both poles

Distribution of Polar Tundra

Human Activities and Numbers

• Due to the harsh climate and thin soils, the polar tundra climate supports very low population numbers, despite its large area
• Around 4 million people live within the Arctic Circle 
• The ten largest settlements are in northern Russia with Murmansk (300,000 people) being the biggest
• Small indigenous groups also occupy the region, such as the Innuit in northern Canada and Greenland, and the Sami of Northern Europe
• These groups migrate with the seasons to be close to food sources
• There are no permanent residents in Antarctica but some scientific research bases support small temporary populations of scientists in the summer months
• Agriculture is mainly subsistence, with low productivity
• Because crops struggle to grow in the thin, frozen soils, peoples’ diets are mainly meat-based and traditional methods of fishing, trapping and hunting secure supplies, alongside reindeer herding
• Development of buildings, roads and industry is restricted by the frozen ground and their design needs to be adapted so as not to melt the permafrost 
• Cruise ships visit the regions during the summer months, bringing much needed income to local economies in the form of adventure tourism
• Commercial fishing and trade occurs in the Arctic during the summer months when sea ice melting allows shipping routes to be accessed
• Polar regions contain vast untapped reserves of oil, gas and other minerals and there is pressure on the regions to exploit these resources

Climate change as it affects Agriculture

Impacts of Climate Change on Agriculture