The Water Cycle
Overview
As evident by just this past year alone, Mother Nature is a force to be reckoned with. The extreme water events she inflicts are particularly devastating and carry with them immense damage to property and life. There is no denying the relation between these worldwide flooding events and climate change. The rise in global temperature has one of the most significant impacts on the water cycle. It causes a greater capacity for air moisture, which leads to greater amounts and frequency of precipitation. These precipitation increases, combined with ill-preparedness for extreme weather, leave our world vulnerable to the destructive and catastrophic damage caused by flooding.
Evaporation & Condensation & Transportation
The water cycle, though very complex, can be simplified as liquid water evaporating into vapor and vapor condensing back into liquid water as precipitation. Heat is the main catalyst for evaporation. The rising temperature breaks the bonds of liquid water molecules and turns them into vapor or gas. Unlike with a pot of boiling water where we can see steam, we can’t usually witness this daily process as it happens across the earth. Studies show that 90% of the evaporation process that feeds the water cycle happens over oceans, lakes, rivers and other large water sources. USGS.gov Those vapors cool and condense into clouds and travel with weather patterns, transporting precipitation to land areas where they finally expel in the form of rain or snow fall.
Infiltration & Evapotranspiration
Precipitation directly affects the Infiltration stage of the water cycle. Rain or snow infiltrate, or absorb, into the subsurface of the earth, creating groundwater. Water will permeate into the soil at different rates and amounts. Some soil and rock is more porous and allows for greater infiltration of precipitation, but other soil is more dense and creates surface runoff, which may flow into streams. The water that sits nears the surface of the earth, supplies food to growing plants. These plants and the excess groundwater on the soil surface levels, when heated by the sun, transpire and evaporate and create water vapor in the air. It is estimated this process makes up about 10% of the air moisture needed for precipitation.
Precipitation
Precipitation is the main source of water across the globe, most of that falling in the form of rain. Clouds in the sky are formed by tiny droplets of condensed water vapor. Some clouds will never reach precipitation, they will evaporate back into the atmosphere. Others, however, will grow large and dense enough to expel rainfall. The tiny water droplets attach to other microscopic particles such as smoke or dust and then collide. When enough collisions occur within a cloud, this produces precipitation. USGS.gov Different climate systems produce varying rainfall totals. As you might suspect, deserts see a mere fraction of the total rainfall as compared to a tropical landscape. On average, “one inch of rain falling on just a single acre results in 27,154 gallons of water.” USGS.gov
Call to Action
Water is essential to the earth. It is the life support of all living things: plants, animals, and of course human beings. However, increased precipitation, by way of torrential rainfall, can cause major destruction, including floods, flash floods, mud slides, and landslides. The loss to human life is especially catastrophic, though homes, businesses, schools, and farmlands all experience the same devastation, some with irreparable damage. Rapid rates of rainfall and already saturated ground or city pavements cannot absorb the magnified amount of rain produced by torrential rain and extreme storms.
It is imperative that we continue to study and find ways to combat and reverse global warming. This should be a unified goal across the world. Since we may not see immediate change in the frequency of extreme weather, it is essential that we be prepared for emergency flood situations and secure the proper equipment to protect our property and life.
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