Soil, water and rain
Droughts are often not God-given and have an human influence through bad land management practices. The soil and its moisture play a crucial role in cloud formation and rain. Interestingly, most rain falls when soil moisture is high. What is the relationship between soil, water and rain? To explain the connection in more detail, we asked Stefan Schwarzer.
Good soils brings rain
betterSoil: Are there connections between soil, water availability and rain formation?
Schwarzer: Yes, indeed. Fertile soil, with lots of air pockets within, acts like a sponge upon a rain event. It infiltrates and stores that water easily and in great amount. Now, this water then is the reservoir for plants, which can – often with the help of mycorrhiza – tap into that water and use it for their needs. Upon photosynthesis, it transpires that water, which again is the basis of potentially new clouds – and thus rain. And, when the water in the soil percolates into deeper layers, it is the foundation of water sources downstream, as well as of the ground water.
Rain comes from oceans and land
betterSoil: Worldwide only 50% of precipitation on land comes from the oceans! Where does the rest 50% come from? And what happens to this moist air?
Schwarzer: Yes, astonishingly, although our planet is occupied by 70% with water, and only 30% with land, on average, 50% of the rainfall on land stems from the land, and 50% only from the ocean. When the moist air from the ocean drifts onto the land, it creates the first rains in the coastal zone. Here, the soil and vegetation now absorbs that water and brings it through evaporation of the soil and transpiration by plants back in to atmosphere, where it can build again clouds. These drift further inland, bringing again rains, and the whole cycle starts again. The further inland we go, the higher is the percentage of water that stems directly from that soil-vegetation process, and can sum up to 80 and even 90% in certain parts of the world, such as eastern China and southern South America.
Water forms cloud
betterSoil: Do soils play a role in cloud building and rain development?
Schwarzer: Yes, although mostly not directly through a evaporation process, but to the largest part through water supply for the plants.