Water, the most abundant resource on Earth, is constantly changing forms and moving around. You can pick any point in the water cycle to begin with. FiltersFast states that “[t]he water cycle describes the movement of water on, above and below the surface of the Earth.” (“The Water Cycle: From Evaporation to Precipitation.”). Water goes through many stages, from liquid, evaporating into condensation, coming back down to earth in rain or snow, then soaking back into the earth’s surface; and there it can either become water again or help a plant.
When in the ocean, water is a liquid. The molecules have plenty of room to “swim” around because the oceans cover a large part of Earth. Water is the most abundant resource on planet Earth. It covers almost seventy percent of the earth’s surface.
Not all water stays in liquid form because it can evaporate into the earth’s atmosphere. The molecules in the water are heated up by the sun or by underwater vents and volcanos. The steam coming off the water rises into the sky. When in the atmosphere, it collects into clouds where they take on the form of condensation.
Now that they are flying high in the atmosphere, they can overlook the place where they just were, as well as the places where they could potentially land in their next form. One form in which they can return to the surface of the earth is water. The particles become too heavy for the clouds to hold them, so they are released in rain. This rain can either infiltrate the soil or run into rivers or lakes. The other form in which they can return to the surface is ice or snow. When they return to the surface as these, they can create packs and stay in one place until they are melted. During the process of being melted, they can both turn into water and begin their journey down the mountain back to the ocean, or they can be evaporated back into the atmosphere once more in the form of steam.
Now that the particles have returned to Earth’s surface, they have a few more paths to choose from. If the rain soaks into the earth, it has even more choices of roads it can take. The water can seep back to the surface in springs or freshwater lakes or rivers. Another road it can take is groundwater storage beneath the surface of the earth. Once in these deep water storages, the hot core of the earth heats these large masses of water like a pot of water. Just like steam is released when you boil water, these underground storages release steam through underwater vents and volcanos back into the ocean. These very things were the reason these molecules were released into the atmosphere in the first place.
When in the surface of Earth, plants can suck water up through their roots and take the water molecules on a whole new journey. When sucked up through the plants straw-like roots, the molecules can be turned into sugars or other molecules in the process of photosynthesis. Another path within the plant releases water back into the atmosphere once again through the plants process of transpiration.
The other road I mentioned these molecules can take is seeping back to the surface in springs or lakes. From here, the molecules reach even another fork in the road. The molecules can heat up again from the sun and be released back into the atmosphere in the form of steam. The molecules also have the choice of making their way through the rivers and lakes and back into the ocean where the cycle began.
When the molecules are in the lakes and rivers, they become nutrients for another species on earth, animals. Animals can come and drink the water to help them survive. Within the animal, the molecules go through the process of being excreted through the animal. When the animal dies, the molecules can either be taken by another animal to go through the same process, they can soak into the earth, or they can be evaporated into the atmosphere.
Water particles can go through quite the journey in their lifetime. There are always so many different options the particles can choose to take (see Fig. 1). Wherever they start, they can go from liquid, to vapor, to liquid again or ice, to soaking into the earth’s surface or soaking into plants.