Tag: evs - i

Temperatures in the mesosphere decrease with altitude. Because there are few gas molecules in the mesosphere to absorb the Sun’s radiation, the heat source is the stratosphere below. The mesosphere is extremely cold, especially at its top, about -90 degree Celsius.  So the correct answer is ' it decreases from -2 to -92 degrees. '

The UV-A radiations are scattered and reach the surface of the earth continually. These are the least harmful radiations. The UV-B and UV-C are the most harmful radiations are capable of burning the human skin within 15 minutes of the exposure. These are absorbed by the ozone layer in the stratosphere. The ozone depletion results in the exposure of the earth surface to the UV-B and UV-C causing immunity problems, skin cancers, chlorophyll bleaching etc.

The temperature at the tropopause, which is the upper boundary of the troposphere, is generally around -50 to -60 degrees Celsius.

Water use is increasing every year since 1950 by 4% to 8%.  Electricity water use increased almost 400% since 1950. The use of irrigation water increased by about 29% since 1950. Maximum water is used to grow food for increasing population. Apart from this, the majority of water is used for thermoelectric power and as public supply.

The ozone layer (ozonosphere) is generally found at altitudes of 15-35 km. The options provided are confusingly phrased regarding poles versus equator, but 12-20 km is a common range for the lower boundary of the ozone layer.

Ozone layer is part of earth's atmosphere. Ozone is basically found in stratosphere. Ozone layer contains high concentration of ozone formed due to reaction of oxygen with UV radiations. It is vital to human life on earth because it absorbs biologically harmful ultraviolet radiations from sun. Direct exposure of such rays can cause serious illness and skin problems. However ozone chemically forming in earth's surface is lethal in many ways.

• Biosphere 2 is an American Earth system science research facility located in Oracle, Arizona at the base of the Santa Catalina Mountains.
• Its mission is to serve as a center for research, outreach, teaching, and lifelong learning about Earth, its living systems, and its place in the universe.
  
• It is a glass dome covering an area of 3.5 acres with 4000 representatives of most ecosystems and eight human beings in order to prepare a prototype of the space colony. 
• So, the correct answer is 'Biosphere 2'.

The ozone layer in the stratosphere absorbs solar UV-B (280-320 nm) which is the most harmful part of the ultraviolet. Thus it acts as protector gas for plants, animals by absorbing harmful UV radiation in the stratosphere and as pollutant around the ground level. Nature intended that the stratospheric ozone layer would block the sun's harmful ultraviolet rays.. (CFC), which contains chlorine, an ozone destroyer.

The concentration of ozone varies with an altitude of the atmospheric layers. Ozone is basically stratospheric gas. The reaction of the oxygen with the UV radiations result in the formation of the ozone layer. Peak concentration, an average of 8 molecules per million molecules occur above the altitude of 30kms from the earth's surface which is roughly 20 miles. This is the height that corresponds to the stratosphere.