How are rocks weathered by salt in semi arid environments and latitudes have sinking air with dry conditions due to atmospheric circulation?
Salt crystallization occurs in semi-arid environments, where the evaporation of water from rock surfaces leads to the crystallization of salts. Crystallization leads to a dramatic increase in volume which exerts pressure on the surrounding rock, and can eventually fracture the rock. Salt weathering is often cited as a highly effective physical weathering process in deserts but it seems more effective in propagating cracks than in forming them. Salt also works to weather rock in a process is iconoclast. Saltwater sometimes gets into the cracks and pores of rock. If the saltwater evaporates, salt crystals are left behind. As the crystals grow, they put pressure on the rock, slowly breaking it apart. Physical forces in the desert that break down rocks include the daily heating and cooling of rocks on the surface, expansion of plant root in cracks, the freezing and melting of ice in cracks, and exposure to wind and precipitation. While water is still the dominant agent of erosion in most desert environments, wind is a notable agent of weathering and erosion in many deserts. This includes suspended sediment traveling in ha boobs, or dust storms, that frequent deserts. 30 degrees N & S Latitudes: air sinks causing a drying effect and many deserts in this region and in the Horse Latitudes because lack of wind caused sailors to become becalmed. 90 degrees N & S Latitudes: air sinks over the poles and moves equator ward. Atmospheric circulation transports heat over the surface of the Earth that affects the water cycle, including the formation of clouds and precipitation events. The movement of air masses brings us our daily weather, and long-term patterns in circulation determine regional climate and ecosystems. Subtropical deserts are caused by the circulation patterns of air masses. They are found along the Tropic of Cancer, between 15 and 30 degrees north of the Equator, or along the Tropic of Capricorn, between 15 and 30 degrees south of the Equator. As the air leaves the equator, it rains away more moisture, becoming denser and slightly cooler, until finally dry, it sinks, creating the arid bands where many of the world's famous deserts lie. In each hemisphere there are three cells in which air circulates through the entire depth of the troposphere. The troposphere is the name given to the vertical extent of the atmosphere from the surface, right up to between 10 and 15 km high.
Atmospheric circulation transports heat over the surface of the Earth that affects the water cycle, including the formation of clouds and precipitation events. The movement of air masses brings us our daily weather, and long-term patterns in circulation determine regional climate and ecosystems. Most of the world's deserts are located near 30 degrees north latitude and 30 degrees south latitude, where the heated equatorial air begins to descend. The descending air is dense and begins to warm again, evaporating large amounts of water from the land surface. The resulting climate is very dry. 30 degrees N & S Latitudes air sinks causing a drying effect and many deserts in this region and the Horse Latitudes because lack of wind caused sailors to become becalmed. 90 degrees N & S Latitudes: air sinks over the poles and moves equator ward. As the air leaves the equator, it rains away more moisture, becoming denser and slightly cooler, until finally dry, it sinks, creating the arid bands where many of the world's famous deserts lie. Salt crystallisation occurs in semi-arid environments, where the evaporation of water from rock surfaces leads to the crystallisation of salts. Crystallisation leads to a dramatic increase in volume which exerts pressure on the surrounding rock, and can eventually fracture the rock. Salt also works to weather rock in a process called haloclasty. Saltwater sometimes gets into the cracks and pores of rock. If the saltwater evaporates, salt crystals are left behind. As the crystals grow, they put pressure on the rock, slowly breaking it apart. Physical forces in the desert that break down rocks include the daily heating and cooling of rocks on the surface, expansion of plant root in cracks, the freezing and melting of ice in cracks, and exposure to wind and precipitation. While water is still the dominant agent of erosion in most desert environments, wind is a notable agent of weathering and erosion in many deserts. This includes suspended sediment traveling in haboobs, or dust storms, that frequent deserts.
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