Normally, the temperature decreases with the increase in height from the Earth's surface, because<br/>1. The atmosphere can be heated upwards only from the Earth's surface.<br/>2. There is more moisture in the upper atmosphere.<br/>3. The air is less dense in the upper atmosphere.<br/><br/>Select the correct answer using the codes given below:

1. Correct. The troposphere is heated mainly from below: the Earth's surface absorbs solar radiation and then warms the air above it by conduction, convection and terrestrial radiation.
2. Incorrect. Moisture is concentrated mostly in the lower troposphere, not the upper atmosphere; this is not the reason for normal temperature decrease with height.
3. Correct. Air pressure and density decrease with altitude, so rising air expands and cools (adiabatic cooling), contributing to lower temperatures aloft.

Hence, 1 and 3 only are correct.