Water
How does water change form and move on Earth?
States of Matter
How does water change it's state?
Water can be found in three different states of matter here on earth, solids, liquids and gasses. All three states are found in the water cycle. We usually think of water as a liquid but depending of the temperature of the water it may be a solid or a gas. For water to be a solid, ice, it must be 0° C or 32° F. Examples of solid states of water include snow and ice. When heat is added to water it makes it warmer and causes it to change states. The first change of state that can occur is when heat is added to ice and causes it to melt into water. This occurs at temperatures above 0° C or 32°F to 100° C or 212°F. When temperatures rise above 100°C it turns into a gas known as water vapor. When the sun heats the water here on earth it evaporates and forms into clouds. When the clouds are cooled the water vapor condenses back into water again. This water can fall as rain, snow or ice.
The Water Cycle
What happens to water on earth?
The path that water travels in is called the water cycle. Over three fourths of the earth is covered in water such as oceans, rivers and lakes. In order for water to enter the water cycle from these bodies of water it must evaporate by the sun heating it and turning it into water vapor. Plants also release water vapor through a process called transpiration. Plants absorb the water through their roots and release the water from the small openings on the underside of their leaves. We also release water into the air when we water our lawns, splash in the pool, or wash our car for examples. When water evaporates only the pure water becomes water vapor so dirt and salt will be left behind.
Once the water vapor cools, it condenses and forms clouds. We see evidence of condensation on the outside of glass on a hot summer day or on the mirror after you take a shower. You can see evidence of condensation outside through dew and frost. Once the water vapor cools and collects in the clouds it will become rain. This happens when the water vapor collects and becomes too heavy for the clouds and then falls back to the earth. Different forms of precipitation include snow, hail and freezing rain.
When the water falls back to the earth it can be absorbed into the soil known as percolation. Water flows through the tiny cracks in the soil and collects above the impermeable rock layer. This becomes known as ground water. If the water cannot be absorbed by the soil it is called surface runoff. Surface runoff can create erosion. Eventually the water will again be evaporated and continue the cycle.