Typically, the water cycle is taught as a simple circular cycle of evaporation, condensation, and precipitation. Although it is a useful model (especially for children to learn the water cycle), the reality is much more complicated. The pathways of water through ecosystems are extremely complex, making it difficult to understand exactly. In fact, the National Office for Oceanic and Atmospheric Administration (NOAA) is currently researching the global water cycle to more accurately forecast weather, water resources, and ecosystem health.
The water cycle on Earth
Water is essential for life on Earth. Furthermore, in its three phases (solid, liquid and gaseous), water forms part of the Earth’s climate system. In other words, it is directly related to the air, clouds, oceans, rivers, vegetation, layers of snow and glaciers, among others. The water cycle shows the continuous movement of water within the Earth and the atmosphere. During this process, liquid water evaporates, condenses to form clouds, and falls back to earth as rain or snow.
Water in its different phases moves through the atmosphere. Thus, liquid water flows through the ground (runoff) to the ground (infiltration and percolation) and through the ground (groundwater). Groundwater, in turn, passes into plants and evaporates through perspiration. On the other hand, solid ice and snow can be converted directly to gas by sublimation. The reverse can also happen when water vapor solidifies (deposition).
Water and climate change
Unfortunately, climate change is affecting the amount of water we have available. Extreme weather events such as droughts, torrential rains or floods (which will increase as the climate changes) could affect the water resources necessary for human life.
These challenges could also alter the economy, energy production, human health, agriculture, and natural ecosystems. Taking care of the planet is in our hands!
