Answer:
Explanation:For the atmosphere, the drop in temperature of rising, unsaturated air is about 10 degrees C/1000 meters (5.5 deg F per 1000 feet) altitude. If a parcel of air is at 24 degrees C at sea level, and it rises to 1000 meters, its temperature will go down to 14 degrees C. If it goes up to 2000 meters, its temperature will go down to 4 degrees C.
4. What will its temperature be at 3000 meters?
The temperature would be minus 6 degrees C.
This rate of temperature change of unsaturated air with changing altitude is called the dry adiabatic lapse rate: the rate of change of the temperature of rising or subsiding air when no condensation is taking place (we’ll talk about the condensation part shortly).
If the air subsides, it also changes temperature. It warms up, and it is warming up at the dry adiabatic lapse rate. So, if the air at 4000 meters altitude has a temperature of -10 degrees C, and it subsides to 3000 meters, its temperature will warm up to 0 degrees C. If it continues to subside, then at 2000 meters, its temperature will be 10 degrees C.
5. What will the temperature of this air be at 1000 meters?
Its temperature would be 20 degrees C.
Make sure you notice that we are talking about moving air (rising or subsiding), not still air. The change in temperature of still air (that is, air that is not rising or subsiding) follows the environmental lapse rate, which varies considerably, but averages about 6.5 deg C/1000 meters (3.6 deg/1000 feet). In still air, if you went up in a hot air balloon, carrying a thermometer and taking the air temperature every 1000 meters, on average the temperature would drop 6.5 degrees C every 1000 meters. The rate of temperature change as you rise in still air is not as great as the rate of change of rising air; that is, the air parcel does not cool off as fast.
For instance, the air temperature at sea level is 28 degrees C. Climb into your balloon, release the tethers, and go up 1000 meters in the still air.
6. On average, what will the air temperature be at 1000 meters?
The temperature will be 21.5 degrees C.
Well, what happens is that the air will still cool off, but not as fast. If water vapor in the air is condensing, the adiabatic rate is lower. The air is only cooling off at a rate of about 5 degrees C/1000 meters (2.7 deg per 1000 feet). This is called the saturated adiabatic lapse rate (or the wet adiabatic lapse rate, or the moist adiabatic lapse rate, depending on the textbook you are using). The saturated lapse rate varies with the original temperature of the air parcel, but 5 degrees C/1000 meters is a commonly used value.
So, let’s assume a rising parcel of air reaches the lifting condensation level at 2000 meters, at a dew point temperature of 12 degrees C. At this point, clouds will form. As the air continues to rise, it will continue to decrease in temperature, but more slowly than it cooled off before condensation began.
11. What will the temperature of this parcel of air be at 3000 meters?
The temperature at 3000 meters will be approximately 7 degrees C. The saturated adiabatic lapse rate is given as 5 deg C/1000 meters, so if you go up 1000 meters, the air will cool off 5 degrees. 12-5=7.