Correct Option
The correct option is Temperature decreases at the rate of 1°C for every 165m..
Explanation
The Normal Lapse Rate refers to the average rate at which temperature decreases with an increase in altitude within the Troposphere. This occurs because the troposphere is primarily heated from below by terrestrial radiation (heat radiated from the Earth's surface) rather than directly by incoming solar radiation.
Detailed Analysis
- Temperature increases at the rate of 1°C for every 165m. is Incorrect: In the Troposphere, temperature decreases with altitude. A situation where temperature increases with altitude is termed Temperature Inversion, which is a deviation from the normal trend.
- Temperature decreases at the rate of 1°C for every 165m. is Correct: The standard accepted value for the Normal Lapse Rate is a decrease of 1°C for every 165 meters of ascent.
- Temperature decreases at the rate of 6.5°C for every 165m. is Incorrect: While the rate is approximately 6.5°C per 1000 meters (1 km), a decrease of 6.5°C per 165 meters would represent an unrealistically steep cooling gradient.
- Temperature remains constant up to 165m. is Incorrect: Temperature does not remain constant; it declines consistently throughout the Troposphere until the Tropopause is reached.
Key Takeaway: The Normal Lapse Rate in the Troposphere is defined as a temperature decrease of 1°C per 165 meters or approximately 6.5°C per kilometer.