What is the standard lapse rate in the troposphere?

What is the standard lapse rate in the troposphere?

• A. 6.5 degrees Celsius per 1000 feet
• B. 3 degrees Celsius per 1000 feet
• C. 1 degree Celsius per 1000 feet
• D. 2 degrees Celsius per 1000 feet

Answer: (D)

Temperature in the troposphere decreases as you go upward at a nearly constant rate in the International Standard Atmosphere. The standard lapse rate is 6.5°C cooler for every 1,000 meters of altitude, which works out to about 2°C cooler for every 1,000 feet. So as you rise, the air cools by roughly two degrees per thousand feet. For example, climbing 5,000 feet would drop the temperature by about 10°C, and 10,000 feet by about 20°C relative to sea level. This rate is used to estimate air density and aircraft performance in standard atmosphere conditions. The other options don’t match the standard rate when expressed in feet: 3°C per 1,000 ft is too steep, 1°C per 1,000 ft too shallow, and 6.5°C per 1,000 ft mixes up the metric rate with feet.

Temperature in the troposphere decreases as you go upward at a nearly constant rate in the International Standard Atmosphere. The standard lapse rate is 6.5°C cooler for every 1,000 meters of altitude, which works out to about 2°C cooler for every 1,000 feet. So as you rise, the air cools by roughly two degrees per thousand feet. For example, climbing 5,000 feet would drop the temperature by about 10°C, and 10,000 feet by about 20°C relative to sea level. This rate is used to estimate air density and aircraft performance in standard atmosphere conditions. The other options don’t match the standard rate when expressed in feet: 3°C per 1,000 ft is too steep, 1°C per 1,000 ft too shallow, and 6.5°C per 1,000 ft mixes up the metric rate with feet.