A study published in the journal Nature claims that climate models may be overestimating the severity of droughts due to global warming. A prevailing opinion is that drier soil will have less water to evaporate, and therefore lead to even less rainfall – intensifying the drought. However, the new study finds that showers are more likely to develop over dry soil than over moist soil. Since there is less water to evaporate from the dry soil, the air can warm more rapidly, creating thermals that rise into the atmosphere, cool and condense into clouds that eventually produce rain. It’s Meteorology 101.
The researchers, led by Chris Taylor from Britain’s Centre for Ecology and Hydrology, looked at global satellite images to determine where clouds/rain were more likely to develop. The found that more showers developed over dry ground than wet ground.
“Both heat and moisture are critical ingredients for rain clouds to build up during the afternoon,” Taylor explained.
“On sunny days the land heats the air, creating thermals which reach several kilometres (miles) up into the atmosphere. If the soil is dry, the thermals are stronger, and our new research shows that this makes rain more likely.”