Soil Moisture Affects Afternoon Rains

New study delves into global data of rain events to explain why soil moisture content is a factor affecting climate

A new study delves into global data of rain events to explain whysoil moisturecontent is a factor affecting climate. Researchers led by the ETH Zurich's Institute for Atmospheric and Climate Science in Switzerland studied the frequency and locations of afternoon rains during summer. They were able to observe this phenomenon - precipitation is more likely to fall in places where the soil is driest compared to nearby areas.

Findings in this new research clarifies and adds new observations on when and where it rains most. Some studies state that it rains more in areas where soil has high moisture content, but this conclusion lacks substantiation. Benoit Guillod, the study's first author and now, a researcher at the University of Oxford, explains that although soil water content influences climate,precipitationfalls most in areas where the soil is driest.

The scientists described how this occurs. High amounts of soil moisture content increases the probability of afternoon rain in summer. The sun's intense rays cause evaporation of water from land during the day. When water vapour reaches cold air layers, condensation takes place and then it rains. However, rain is most likely to fall on dry lands. Why is it so? On hot days, the warm moist air that evaporates from places with less soil moisture recede highest and bump into cold-air mass soonest. Thus, rain falls oftentimes on these sub-regions.

Studies on soil moisture as a climatic factor require constant monitoring of atmospheric processes, soil moisture content and other related elements. The Institute for Atmospheric and Climate Sciences in Switzerland is one of the pioneers in this field since 2008. ETH has worked together with Agroscope Reckenholz-Tänikon and MeteoSwiss to set-up 19 soil sensors across Switzerland for monitoring moisture content, soil temperature, and radiation. Although satellite data could provide information about water content on the soil's surface to a depth of 3 centimetres, scientists opt to study soil moisture content at one-metre depth for a more accurate investigation.

Source: International Business Times

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