Explain temperature inversion.

Temperature inversion is a meteorological phenomenon where the normal temperature decrease with altitude is reversed, and a layer of cooler air is trapped beneath a layer of warmer air. Normally, the air near the Earth's surface is warmer than the air above it because the surface absorbs sunlight and warms the air above it through conduction. However, during a temperature inversion, this typical situation is inverted.

Here's a step-by-step explanation of how a temperature inversion occurs:

1. During the day, the sun heats the Earth's surface, causing the air in contact with it to warm up as well. 2. As warm air is less dense, it rises and is replaced by cooler air from above, leading to a gradual decrease in temperature as altitude increases. 3. Under certain conditions, such as clear nights, long nights during winter, or when there is a strong high-pressure system, the ground cools rapidly by radiating its heat away. 4. If the air is calm and does not mix, the air close to the ground can become cooler than the air above it. 5. Sometimes, a layer of warmer air moves above the cooler air at the surface, particularly when a warm front passes over an area or when warm air blows in from a different altitude. 6. This layer of warmer air above cooler air acts as a cap and prevents the cooler air from rising. Thus, the usual vertical movement of air is inhibited, and the cooler air is trapped beneath the warmer air.

Temperature inversions can lead to various environmental effects, such as smog, because they trap pollutants near the Earth's surface, leading to poor air quality. They can also create unusual sound propagation conditions, allowing sounds to travel further and clearer than usual.