This week for homework we had to write a report on the Water Cycle
The Water Cycle
How has the water cycle continued to fulfill the earth with a good stable water supply.
What water is made of.
You may know that water's chemical composition is H20. A water molecule contains 2 hydrogen (H) atoms and 1 oxygen (O) atom.
One molecule of water in your glass won't quench your thirst, though. You need LOTS of water molecules, trillions of them. At normal temperatures all those individual water molecules like to stick together and form a liquid (the water in your glass).
Because of the way that the hydrogen and oxygen atoms exist in a water molecule, one water molecule is attracted to another water molecule. The opposite sides of a water molecule stick to each other just as opposite sides (poles) of magnets do.
Like a magnet, one side of the water molecule (the side with the oxygen atom) has a negative electrical charge while the other side, where the hydrogen atoms sit, has a positive charge. Since opposite charges attract each other, water molecules attract each other. So much so that when trillions of them get together, they often start sticking to each other and, thus, you have liquid water.
Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. ... Leaf surfaces are dotted with pores called stomata, and in most plants they are more numerous on the undersides of the foliage.
The Next stage is
Evaporation
For the water cycle to work, water has to get from the Earth's surface back up into the skies so it can rain back down and ruin your parade or water your crops or yard. It is the invisible process of evaporation that changes liquid and frozen water into water-vapor gas, which then floats up into the skies to become clouds.
As usual, you can thank the sun for keeping evaporation going. The sun's energy breaks the bonds that hold liquid water molecules together. Thus, it makes sense that water evaporates more easily in hot conditions, such as in the desert, rather than on a cloudy winter day.
The amount of water vapor in the air is known as "humidity", often mentioned in the weather reports on the local news. When warm air containing a lot of water vapor (high humidity) moves into colder temperatures (either high in the atmosphere or even on the outside of your glass of iced tea), the colder temperatures cause water vapor to condense into a liquid. The colder temperatures cause water vapor to condense into water droplets and can result in fog.
The Next stage is condensation
All air contains water molecules in the form of water vapor, which is invisible. Since the water cycle is all about water changing forms all the time, how does the water vapor turn from a gas back into a liquid and become rain?
The word is "condensation". Water vapor gas condenses back into liquid water and ice, which you mainly see as clouds and then as rain and snow.
Condensation happens because of temperature changes. Warmer air can contain more water vapor than colder air, so when air rises up from the heated earth's surface high into the sky (warm air rises, of course), to where the temperatures are much colder, condensation happens. Some of the water vapor in the cold air high in the sky just cannot stay a gas, and condenses into tiny liquid water droplets—the clouds you see every day. Give it time, the liquid water comes down as rain.
Another important part is The Sun
The real boss of the water cycle doesn't even live here on Earth. The sun is what makes the water cycle work. The sun provides what almost everything on Earth needs to go—energy, or heat.
The sun is so big that even at over 90 million miles you can feel its heat. The sun's energy affects water at its smallest level - the molecular level. Liquid water contains water molecules stuck together. The energy from the sun can break apart these tightly-held molecules into much smaller sets of water molecules, which results in tiny water vapor particles, an invisible gas. This process allows liquid water to evaporate into water vapor, which in the main way water gets from the land surface and oceans back into the sky.
The sun also participates in moving water around the Earth. Different parts of the world (and even your neighborhood) are heated to different levels by the sun, and unequal heating and cooling of parts of the landscape causes air to move around from here to there—the winds. You know that the winds move clouds and the weather all over the place; all of this mixing up and moving is an important part of the water cycle.
Another important part is Runoff
Runoff is nothing more than water "running off" the land surface. Just as the water you wash your car with runs off down the driveway as you work, the rain that Mother Nature covers the landscape with runs off downhill, too (due to gravity).
Even though some rainfall soaks into the ground, most of it flows over the land surface, going downhill. This runoff water reaches rivers, lakes, and the oceans, keeping the water cycle going.
Runoff is also important because as it flows over the land, some of it soaks into the ground, thus "recharging" groundwater, providing plants with water for their roots to take up so they can create the delicious beets and spinach you like so much, and keeps underground aquifers (areas underground full of water) full so people can drill a well and pull the water out for their own purposes.
And this is how the water cycle has continued for millions of years and if we can help the environment it will continue to sustain us for the years up coming.
By Halle
