During summer, the air over the plateau is warmed by the sun's radiation. As the warmed air rises, air from the surrounding lowlands of India and Bangladesh are drawn towards the Himalayas. This moist air is forced upward, helping to generate the heavy monsoon rains. Thus, the Asian monsoon is more like a giant mountain breeze than a sea breeze. Using a blend of satellite, upper air, and ground based observations, Bannon and a graduate student have quantified the surface radiation budget for the monsoon and shown that the radiative warming over Tibet is twice that over the surrounding regions.
Mountains also help create deserts.
Air dried by its ascent over the Tibetan plateau arrives over central Asia with too little moisture to produce precipitation. In South America, the blocking of the surface winds by the Andes prevents rising motion and precipitation. This results in the coastal desert of Chile and Peru, where the town of Iquiqui has gone as long as ten years without measurable precipitation. While primarily a theoretician, Bannon has also participated in the Alpine Experiment. This international field program studied mountain waves, lee cyclones, and frontal distortion over the European Alps.