• # question_answer Consider the following statements about a particular layer of the atmosphere. 1. It contains about three-fourth of the total mass of the atmosphere. 2. There is fall in temperature with increasing height. 3. Its height is more at equator than at the poles. 4. All the weather phenomena occur in this layer. Identify this layer A)  Ionosphere        B)  Mesosphere C)  Stratosphere      D)  Troposphere

[d] Ionosphere: The ionosphere overlaps the other atmospheric layers, from above the Earth. The air is ionized by the Sun's ultraviolet light. These ionized layers affect the transmittance and reflectance of radio waves. Mesosphere: The mesosphere is above the stratosphere. Here the atmosphere is very rarefied, that is, thin, and the temperature is decreasing with altitude, about $-\,130$ Fahrenheit ($\begin{array}{*{35}{l}} -\,90 \\ \end{array}$Celsius) at the top. Stratosphere: The stratosphere is found from about 7 to 30 miles ($11-48$ kilometres) above the Earth's surface. In this region of the atmosphere is the ozone layer, which absorbs most of the harmful ultraviolet radiation from the Sun. The temperature increases slightly with altitude in the stratosphere. The highest temperature in this region is about 32 degrees Fahrenheit or 0 degrees Celsius. Troposphere: This is the lowest atmospheric layer and is about seven miles (11 km) thick. Most clouds and weather are found in the troposphere. The troposphere is thinner at the poles (averaging about 8 km thick) and thicker at the equator (averaging about 16 km thick). The temperature decreases with altitude.