Ans: C

Exp: 

Statement 1 is incorrect: The density of the Atmosphere is highest near the surface of the earth, and it decreases, not increases, with increasing altitude. Thus, at higher altitudes, we have the thinnest atmosphere.

Statement 2 is incorrect:  The thickness of the troposphere is thicker at the equator because of the rise of warm conventional air currents and thinnest at both the southern and northern pole regions due to the subsidence of the cold winds.

Atmospheres based on temperature conditions are in order as troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The ionosphere is the ionised part of the upper atmosphere of Earth, a region that includes the thermosphere and parts of the mesosphere and exosphere.

Ans: A

Exp:

Statement 1 is correct: In general, water vapour present in air decreases from the equator towards poles. In warm and wet  tropics , water vapour may account for four percent  while in dry and cold areas of desert and polar regions it may be less than one percent of air . 

Statement 2 is incorrect : Higher concentration of dust particles is found in subtropical and temperate regions due to dry winds in comparison to equatorial and polar regions . Dust particles are generally concentrated in lower layers of the atmosphere , yet conventional Air currents may transport them to higher altitudes .  

Statement 3 is correct :  Carbon dioxide present in the atmosphere soaks up  infrared energy, it vibrates and re-emits the infrared energy back in all directions  and contributes to the ‘greenhouse effect ‘ which further causes global warming.

Ans: D

Exp:

Insolation is the energy received by planet Earth through incoming solar radiation. The Earth’s surface receives most of its energy in short wavelengths. The amount and the intensity of insolation vary during the day, in a season and in a year. The factors that cause these variations in insolation are :

• the angle of inclination of the sun’s rays; Hence, Statement 1 is correct.

• the length of the day; 

• the transparency of the atmosphere; Hence, statement 2 is correct.

• the configuration of land in terms of its aspect/ orientation; Hence , statement 3 is correct.

• the rotation of the earth on its axis; Hence, statement 4 is correct.

The last two, however, have less influence. Earth’s axis makes an angle of 66½ with the plane of its orbit around the sun has a greater influence on the amount of insolation received at different latitudes.

Ans:  B

Exp:

A Temperature inversion is a layer in the atmosphere in which air temperature increases with height. The following are the causes of Temperature inversion:

• Long winter nights with clear skies 
• Calm and still vertical winds to prevent intermixing of distinct temperature layers 
• Reversal in normal lapse rate

The inversion takes place in hills and mountains due to air drainage. Cold air in the hills and mountains, produced during the night, flows under the influence of gravity. Being heavy and dense, the cold air acts almost like water and moves down the slope to pile up deeply in pockets and valley bottoms with warm air above. This is called air drainage.

Ans: A

Exp:

The Coriolis force acts perpendicular to the pressure gradient force. The pressure gradient force is perpendicular to an isobar. The higher the pressure gradient force, the more is the velocity of the wind and the larger is the deflection in the direction of wind. As a result of these two forces operating perpendicular to each other, in the low-pressure areas, the wind blows around it. This flow of air in a circular fashion is called a cyclone. As the Coriolis force at the equator is zero, it prevents the intensification of the low pressure in the tropical regions. Thus tropical cyclones are not formed at the equator.