|A 4th grade activity for the water or the hydrologic cycle. A reading passage with questions for the water cycle for Earth science in grade 4. The planet Earth is a very wet planet that has over 70% of its surface covered in water. Water has been on earth for almost four billion years! The earth has had |
almost the same about of water now as it did almost four billion year ago. Most of this water is made up by the five oceans which are saltwater. The rest of the water takes the form of ice on the north and south poles, or found in lakes, rivers, soils, which is ground water and the clouds. The two types of water found on earth are either salty or fresh. The water on earth cycles between the oceans, the land and the air and is always on the move. As the water circulates, it changes from one state to another, solid, liquid and gas. This continuous cycle where water moves from the surface of the earth to the atmosphere is called the water cycle. The water cycle is powered by the heat from the sun. Water is always on the move. Evaporation occurs when the water changes from a liquid to a gas. Evaporation is as though the water disappears, however, it is changing states. The liquid form is easier to see that the vapor/gas form. Water vapor is the gas form of water. Condensation occurs when water changes from a gas (water vapor) to a liquid. Droplets of dew are a form of condensation. Precipitation occurs when water falls from the atmosphere to the ground. Examples of precipitation are hail, rain, sleet and snow. Transpiration is when evaporation happens through plants. The movement of water is constant and it repeats over and over again which is why it is referred to as the water cycle. Another name for the water cycle is the hydrologic cycle.