Fundamentals of Geography. Study guide

Carbon dioxide plays a huge role in the geographical envelope, being the main

“The areas of each of them form climatic zones (Fig. 11). There are five types of climate, but there are nine climatic zones, since all types of climate, except equatorial, can be seen in the northern and southern hemispheres again.

“The equatorial belt. In the lowest latitudes, up to about 5–10° from the equator in the Northern and Southern Hemispheres, an equatorial type of cli­mate is developed with uniformly high air temperatures throughout the year and fluctuations in average monthly temperatures ranging from 24 to 28 °C with two subtypes: zenithal rains and tropical monsoons. The equatorial climate of

zenith rains is very humid (2000–3000 mm per year or more), with daily after­noon showers accompanied by almost continuous thunder and lightning. A sunny morning, showers with thunderstorms in the afternoon, a clear sunset and a moonlit night are from day to day all year round” (Milkov, 1990). “The most typical equatorial climate of zenithal rains is represented in the basins of the Amazon and Congo rivers, the Malacca Peninsula, and the Sunda Islands. The climate of the tropical monsoon. Areas with uneven distribution of precipi­tation throughout the year. For example, in Manaus (Brazil), in the Amazon low­land, from June to October, in the winter season of the Southern Hemisphere, only 377 mm of precipitation falls with an annual total of 2001 mm. In Libreville, the capital of Gabon, half a degree north of the equator, from October to May inclusive, 200 to 380 mm of precipitation falls monthly, and in July it is only 3 mm of precipitation. The dry period in the equatorial belt is associated with the movement of zenithal rains in the northern (July) and southern (January) direc­tions and trade winds here. This is how the climate of tropical monsoons is formed in the equatorial belt” (Milkov, 1990).

Tropical belts. They can be seen to the north and south of the equatorial belt. Its boundary in the north and, accordingly, in the south of the southern hemisphere is (approximately) latitude 30 °. Tropical air dominates here all year round. “Com­pared with the equatorial belt, the cloud cover in the tropical belt is somewhat lower, the air temperature in the northern tropical one is higher, and in the southern it is lower. The average temperature of the coldest month at sea level area, with the exception of cold currents, is not lower than 16 °C” (Milkov, 1990). “The an­nual temperature amplitude goes up. The amount of moisture of the tropical belt is much lower than the equatorial one, and the annual precipitation decreases when moving to higher latitudes to the outer (polar) boundaries of the belt. Precipitation is very unevenly distributed inside the belt. Their quantity and intra-annual regime are determined by circulation processes. Depending on the moisture content, three subtypes of tropical climate are recognized: trade winds, tropical monsoons, and inland deserts. The trade wind climate is typical for the oceans. Its characteristic features include moderate steady wind with the eastern component, low clouds, low precipitation. There is one important feature in the geography of precipita­tion – an insignificant amount of it (250–100 mm or less) in the extreme east of the oceans and an increase in precipitation up to 1000 mm or more in the western sectors of the oceans. The climate of tropical monsoons restricts itself mainly by

South and Southeast Asia, the north of Australia with adjacent oceanic waters. With an increased amount of precipitation compared to the trade wind climate, it is distributed unevenly here: the winter dry and summer rainy periods are quite distinct. The annual precipitation varies widely from 1000 mm or less to 2000–3000 mm or more on the windward slopes of the mountains. The climate of tropical deserts (Sahara, Arabia, etc.) is characterized by exceptionally hot sum­mers and extreme poverty of precipitation. The average temperature of July in the

trated.

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As you can see, the lowest rates of water renewal are typical for polar glaciers (the so-called preserved hydrosphere); that is associated with the transition of wa­ter from liquid-phase state to solid, and it is very slow flow. We’ll single out the amount of fresh water on Earth, that is “one of the most valuable natural resources. There are 36,7 million km3 of fresh water on the planet (2,65 % of the total volume of water). The main accumulators of fresh water are glaciers, fresh groundwater, underground ice in the permafrost zone, fresh lakes. Of the total amount of fresh water on Earth, the solid phase (ice) accounts for 71 %, the liquid phase – 29 %” (Bobkov, 2012).

According to modern concepts, the hydrosphere was formed by melting and degassing the substance of the inner layers of Earth (mantle) and their further con­densation on the surface. Initially, there was a slow increase in the volume of the surface hydrosphere, because significant amount of water, received as a result of degassing of the mantle, was used for hydration of mineral matter, for processes which turn rocks into granite, and then for formation of chemically bound waters during sedimentary rock formation. The increase in the mass of the free hydro­sphere began when the rate of release of bound waters in rocks exceeded the rate of their accumulation (Bobkov, 2012). At the same time, there was an influx of juvenile waters. The Phanerozoic (especially Meso-Cenozoic) was characterized by the formation of oceanic depressions, and the growth of water mass in the sur­face hydrosphere.

condenses and falls to the ground in the form of precipitation under the influence of gravity” (Milkov, 1990).

The most important feature of seawater is salinity. In the open ocean, the average salinity is 35 %, i.e. 1000 g of water contains 35 g of salts. The compo­sition of sea salt is as follows: NaCl – 77,76 %; MgCl2 – 10,87 %; MgSO4 – 4,74 %; CaSO4 – 3,6 %; K2SO4 – 2,465 %; CaCO3 – 0,345 %; MgBr2 – 0,217 %. In addition to chlorides, sulfites and carbonates, almost all chemical elements known on Earth can be found in seawater. “The content of most elements in sea­water is negligible, for example, only 0.008 mg of gold was detected in a cubic meter of water. Conclusions about the presence of certain elements in marine waters are made by their presence in the blood of marine animals and bottom sediments (for example, tin, cobalt)” (Milkov, 1990). The amount of nitrogen and phosphorus compounds is relatively low. The salinity of the ocean is a vari­able value and depends on the climate, the processes of formation or melting of ice, sea currents, the inflow of fresh river waters. Experiencing fluctuations in the amount of dissolved salts, seawater is characterized by the constancy of their ratio to each other. It persists in various parts of the ocean, on its surface and in deep layers.