Question

Explain why
(a) There is no atmosphere on the moon.
(b) There is a fall in temperature with an increase in altitude.

Answer 1

Hint: (a) The escape velocity of moon is less than the root mean square velocity of the moon. Hence, the molecules of gas escape from the surface of the moon.
(b) Temperature generally decreases with increase in altitude. Usually in the troposphere temperature decreases. The gases in the troposphere absorb radiation and thereby decrease the temperature.

Complete answer:
(a) The escape velocity of the moon is less than the root mean square velocity of the moon. Hence, the molecules of gas escape from the surface of the moon. The moon doesn’t have an atmosphere because the magnetic field is weak on the surface of the moon. Since the surface of the moon doesn’t absorb a measurable quantity of radiation the gas molecules are lost into space. The surroundings of the moon are vacuum. But in case our planet, it has more mass and a strong magnetic field. So that the earth has an atmosphere. Whereas, the moon has no atmosphere.

(b) Temperature generally decreases with increase in altitude. This is because of the low pressure in that area, the temperature decreases. Temperature and pressure are interrelated. Usually in the troposphere temperature decreases. The gases in the troposphere absorb radiation and thereby decrease the temperature. Pressure also decreases with height. Pressure at some point is the mass of the atmosphere. The other factors influencing the temperature are latitude, altitude, distance from sea, humidity etc.

Note:
(a) The moon doesn’t have an atmosphere because the magnetic field is weak on the surface of the moon. Since the surface of the moon doesn’t absorb a measurable quantity of radiation the gas molecules are lost into space.
(b)Temperature generally decreases with increase in altitude. Usually in the troposphere temperature decreases. The gases in the troposphere absorb radiation and thereby decrease the temperature.