Temperature inversion occurs when

Analyze the question: It asks you to define temperature inversion, a concept from climatology (atmosphere).

Explain the concept: Normally, in the troposphere, temperature decreases with increasing height. This is called the normal lapse rate, about 6.5°C per 1,000 m. A temperature inversion is the reverse of this: a layer of the atmosphere where temperature increases with height instead of falling.

How it happens (e.g. on calm, clear nights):

1. The ground loses heat quickly by radiation.
2. The air touching the ground cools more than the air above it.
3. A layer of cold, dense air sits under warmer air above, so temperature rises with altitude.

Inversions trap smoke, dust, and fog near the ground. This is why harmattan haze and morning fog can linger in some areas.

Check each option:

• A. Warm air rises over cold air in the tropics: This describes air movement or convection, and it is not limited to the tropics. It is not the definition of an inversion.
• B. Temperature remains the same with height: This is an isothermal condition, not an inversion.
• C. Temperature increases with horizontal distance: This concerns horizontal temperature gradients, not vertical ones.
• D. Temperature increases with height: This is correct. It is the reverse of the normal pattern.

Tip: Think of "inversion" as "turned upside down." Normally it gets colder as you go up. In an inversion, it gets warmer as you go up.