Highlight the variations between the troposphere and stratospheric in the ozone generation and function. Talk about the several approaches to lessening the effects of tropospheric ozone. (Answer in 250 words)
A desert is an extremely dry area of land with extreme environments and sparse vegetation. They are likely to develop in areas where annual precipitation is less than 250 mm. It is one of Earth's major types of ecosystems, supporting a community of distinctive flora and fauna specially adapted to thRead more
A desert is an extremely dry area of land with extreme environments and sparse vegetation. They are likely to develop in areas where annual precipitation is less than 250 mm. It is one of Earth’s major types of ecosystems, supporting a community of distinctive flora and fauna specially adapted to the harsh environment. 
Geologists group deserts into five categories:
- Subtropical deserts: 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, where convection cells diverge. They are caused by the circulation patterns of air masses. Hot, moist air rises into the atmosphere near the Equator. As the air rises, it cools and drops its moisture as heavy tropical rains. The resulting cooler, drier air mass moves away from the Equator. As it approaches the tropics, the air descends and warms up again. The descending air hinders the formation of clouds, so very little rain falls on the land below. Subtropical deserts include the Sahara Desert in Northern Africa, the Kalahari Desert in Southern Africa, and the Tanami Desert in Northern Australia.
- Coastal Deserts: Cold Ocean currents contribute to the formation of coastal deserts. They are generally found on the western edges of continents near the Tropics of Cancer and Capricorn. Winter fog, produced by upwelling cold currents, frequently blankets coastal deserts and blocks solar radiation. The heavy fog drifts onto land. Although humidity is high, the atmospheric changes that normally cause rainfall are not present. For example, the cold Humboldt Current flowing from Antarctica to Southern Chile creates the Atacama Desert of South America, while the cold Benguela Current is critical to the formation of the Namib Desert.
- Rain Shadow Deserts: These deserts exist near the leeward slopes of some mountain ranges. When moisture-laden air hits a mountain range, it is forced to rise. The air then cools and forms clouds that drop moisture on the windward (wind-facing) slopes. When the air moves over the mountaintop and begins to descend the leeward slopes, there is little moisture left. The descending air warms up, making it difficult for clouds to form. For example, the Death Valley, in the U.S. is in the rain shadow of the Sierra Nevada mountains. Similarly, the Patagonian Desert lies in the rain shadow position on the leeward side of the Andes.
- Interior Deserts: They are found in the heart of continents. By the time air masses from coastal areas reach the interior, they lose all their moisture. They are sometimes called inland deserts. For example, the Gobi Desert in China and Mongolia.
- Polar Deserts: Parts of the Arctic and the Antarctic are classified as deserts. They are very dry, but not in the traditional sense. Unlike other types of deserts, they are cold all year round with frigid winters. Instead of sand, the surrounding surface is covered in layers of ice and snow. They experience little precipitation because, above 66°N and S latitude, there is very little moisture in the air due to extreme cold temperatures.
Deserts are found on every continent and cover about one-fifth of Earth’s land area. They are home to around 1 billion people-one-sixth of the Earth’s population. It has been observed that in semi-arid areas that border deserts, climate change and human activities have led to increased desertification.
See less
However, the Intergovernmental Panel on Climate Change (IPCC) in its recent report highlighted that AMOC is losing its stability and is very likely to decline over the 21st century due to the following reasons:
(i) The Mediterranean climatic regions are found in the western parts of the continents within the latitudinal zone of 30°-45° in both hemispheres. The Sub-Tropical High-Pressure Belts extending between 30°-35° latitudes are characterized by dry trade winds during the summer season and anti-cyclonic conditions. This belt extends up to 40° latitudes in the Northern hemisphere at the time of summer solstice and in the Southern hemisphere at the time of winter solstice. Thus, the western parts of the continents within the zone of 30°-40° latitudes do not receive rainfall during the summer season. On the other hand, the Sub-Tropical Belt shifts towards the Equator at the time of winter solstice in the Northern hemisphere and at the time of summer solstice in the Southern hemisphere. Consequently, the zone is characterized by the Westerlies, which lead to precipitation during the winter season. The Mediterranean type of climate is thus characterized by dry summers and wet winters. (ii) The regions lying between 60°-70° latitudes are characterized by two types of winds in a year. With the northward migration of the sun at the time of summer solstice, the Polar Easterlies are weakened because the Westerlies extend over these areas due to the northward shifting of Sub-Polar Low-Pressure Belts. The situation is reversed at the time of winter solstice when there is southward migration of the sun. The Polar Easterlies are re-established between 60°-70°N because of the shifting of the belt of the Westerlies southward. Consequently, it creates a climate characterized by wet summers through the Westerlies and associated cyclones and dry winters due to Polar Easterlies. (iii) Monsoon climate is also the result of the shifting of pressure and wind belts. Due to the northward migration of the sun in the Northern hemisphere at the time of summer solstice, the North Inter-Tropical Convergence Zone (NITCZ) is extended up to 30°N latitude over the Indian subcontinent, Southeast Asia, and parts of Africa. Thus, the Equatorial Westerlies are also extended over the aforesaid regions, which become the southwest or summer monsoons. These southwest monsoon winds bring much rain because they come from over the ocean and are associated with tropical cyclones. The NITCZ is withdrawn from the Indian subcontinent and Southeast Asia because of the southward shifting of pressure and wind belts due to the southward migration of the sun at the time of winter solstice. Thus, north-east trades are re-established which leads to the north-east or winter monsoons. Since they come from over the lands, they are dry.
Ozone (03) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth's upper atmosphere (stratosphere) and lower atmosphere oxygen (troposphere). Depending on where it is in the atmosphere, ozone affects life on Earth in either goodRead more
Ozone (03) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth’s upper atmosphere (stratosphere) and lower atmosphere oxygen (troposphere). Depending on where it is in the atmosphere, ozone affects life on Earth in either good or bad ways. Formation of tropospheric and stratospheric ozone Tropospheric or ground-level ozone is formed primarily from photochemical reactions between two major classes of air pollutants, volatile organic compounds (VOCs) and nitrogen oxides (NOx). NOx and VOC break apart in the presence of intense sunlight and recombine into new structures, creating ozone. It is created by human activities as emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapor, and chemical solvents are some of the major sources of NOx and VOC. On the other hand, stratospheric ozone is formed naturally through the interaction of solar ultraviolet (UV) radiation with molecular oxygen (02). Solar ultraviolet radiation breaks apart one oxygen molecule (02) to produce two oxygen atoms (20) and each of these highly reactive atoms combines with an oxygen molecule to produce an ozone molecule (03). These reactions occur continually whenever solar ultraviolet radiation is present in the stratosphere. Role of tropospheric and stratospheric ozone The tropospheric ozone or bad ozone can trigger a variety of health problems including chest pain, coughing, and throat irritation. It is also a major component of urban smog, which can worsen bronchitis and emphysema, trigger asthma, and permanently damage lung tissue. Further, bad ozone also damages vegetation and ecosystems as it leads to reduced agricultural crop and commercial forest yields, reduced growth and survivability of tree seedlings, and increased susceptibility to diseases, pests, and other stresses such as harsh weather. Whereas, the stratospheric ozone absorbs a portion of UV (Ultra Violet) light called UVB from the sun, preventing it from reaching the planet’s surface. Thus, it protects from many harmful effects, including skin cancers, cataracts, and harm to some crops and marine life. But this good ozone is gradually being destroyed by man-made chemicals referred to as ozone-depleting substances (ODS), including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), etc.
Strategies to prevent the formation of tropospheric ozone.
The Government has further taken initiatives such as the National Clean Air Programme (NCAP), Graded Response Action Plan (GRAP), etc. to check ozone pollution and improve air quality. There is a need for the effective implementation of multi-faceted programs to cut NOx and VOC emissions from vehicles, industrial facilities, and electric utilities. Voluntary programs may also be started to encourage the communities to adopt practices, such as carpooling, to reduce harmful emissions.
See less