The troposphere is the lowest layer of Earth’s atmosphere. It extends from the surface of the Earth to an average height of about 12 kilometers (7.5 miles). The troposphere is where most of Earth’s weather occurs. The air in the troposphere is warmest near the surface of the Earth and gets cooler with increasing altitude. This is because the Earth’s surface absorbs energy from the sun and heats the air. The warm air rises, and the cooler air sinks. This circulation of air creates winds.
The stratosphere is the next layer of Earth’s atmosphere. It extends from the top of the troposphere to an average height of about 50 kilometers (31 miles). The stratosphere is much cooler than the troposphere. This is because the ozone layer, which absorbs harmful ultraviolet radiation from the sun, is located in the stratosphere. The ozone layer helps to protect life on Earth from the sun’s harmful rays.
The mesosphere is the third layer of Earth’s atmosphere. It extends from the top of the stratosphere to an average height of about 85 kilometers (53 miles). The mesosphere is the coldest layer of Earth’s atmosphere. The temperature in the mesosphere can drop to -100 degrees Celsius (-148 degrees Fahrenheit).
The thermosphere is the fourth layer of Earth’s atmosphere. It extends from the top of the mesosphere to an average height of about 600 kilometers (373 miles). The thermosphere is the hottest layer of Earth’s atmosphere. The temperature in the thermosphere can reach up to 2,000 degrees Celsius (3,632 degrees Fahrenheit).
The exosphere is the outermost layer of Earth’s atmosphere. It extends from the top of the thermosphere to an average height of about 10,000 kilometers (6,214 miles). The exosphere is very thin and contains very little gas. The gas molecules in the exosphere are so far apart that they rarely collide with each other.
The correct answer is (a). The troposphere is the layer of Earth’s atmosphere that is nearest to the Earth.