The Water Cycle The student knows that the water cycle is influenced by temperature, pressure, and the topography of the land. Today, we are going study the water cycle and how it is influenced by temperature, pressure, and the topography of the land. SC.D.1.2.3

Evaporation The process by which the Sun heats up the liquid water and changes it into water vapor. Evaporation, condensation, and precipitation are the three main parts of the water cycle. Evaporation is the process by which the Sun heats up the liquid water and changes it into water vapor. This vapor rises into the atmosphere as the warm air ascends.

Condensation The process in which a gas (water vapor) is changed to a liquid as the temperature drops (air cools). Condensation is the process in which the water vapor, a gas, is changed into a liquid as the temperature drops, causing the air to become cooler. Condensation causes clouds to form.

Precipitation The process in which the temperature gets so warm that the clouds fill up, causing the water to fall to Earth as rain, snow, sleet, or hail. When the temperature gets so warm, the clouds fill up, and the water falls to Earth as rain, snow, sleet, or hail. This is called precipitation.

Runoff (Surface Water) The moving of water across the land and back into bodies of water. When precipitation occurs, the water moves across the land and trickles back into the bodies of water. This is the definition of runoff or surface water.

Water Cycle Condensation Precipitation Evaporation Runoff This continuous movement of water is called the water cycle. In this illustration, you can see the water from the ocean being evaporated by the Sun up into the atmosphere. The clouds are forming due to condensation. The precipitation is falling back to the Earth, and finally, the runoff of water is flowing back into the ocean. And after all of that, the water cycle starts right back over again. Evaporation Runoff

Sorting Condensation Evaporation Precipitation Let’s see if you can determine which phase of the water cycle is occurring in each picture. Look at this pot of boiling water. What phase of the water cycle is happening here? (Wait for student response.) Yes, you are absolutely right. Evaporation. The water is being evaporated into the air. If the pot is left boiling for too long, all the water will eventually evaporate into the atmosphere. How about this picture of the raindrops from the cloud? (Wait for student response.) Good job! This is an example of precipitation. But, remember, precipitation can also fall to the Earth as snow, sleet, or hail. Lastly, take a close look at the water droplets on this container of liquid. What part of the water cycle is this? (Wait for student response.) Good answer. This is condensation. I can bet, you’ve probably seen condensation on a glass of ice cold water or soda.

Factors Affecting the Water Cycle Temperature The measure of how hot or how cold something is. Pressure The weight of all of the air above you. The shape of the land from flat surfaces to mountain tops. Topography The water cycle, as magnificent as it may seem, is affected by several factors including temperature, pressure, and topography. Temperature is the measure of how hot or cold something is. Pressure is the weight of all of the air above you. You’ve probably heard your favorite meteorologists talk about temperature and pressure on the evening news. Topography means the shape of the land from flat surfaces to mountain tops.

Temperature Affects the Water Cycle Solar energy powers the water cycle. Temperature speeds-up the water cycle. When the temperature increases, water evaporates faster. Solar energy from the Sun directly affects the water cycle by giving it power. As the temperature increases, meaning as it gets warmer outside, the water cycle speeds up. This is because water evaporates much faster at warmer temperatures.

Pressure Affects the Water Cycle When the air pressure is lower, the water vapor rises faster. Pressure speeds up the water cycle. L You are probably wondering how the pressure of the air could possibly have any affect on the water cycle. Well, the lower the air pressure, the faster water vapor rises. Low pressure speeds up the water cycle, where as, high pressure slows down the water cycle. Pressure slows down the water cycle. H

Topography Affects the Water Cycle Slows down the Water Cycle When the dry air loses its moisture, it moves down the mountain, losing moisture as it continues downward. Therefore, the opposite side of the mountain gets very little rain. Topography is the shape of the land. When the moist air from the oceans move up the mountain range, the air cools, causing the water vapor to condense and eventually fall back to the Earth as rain or snow. Speeds up the Water Cycle Finally, the topography of the land affects the water cycle. Remember, that topography simply means the shape of the land. When the dry air loses its moisture, it moves down the mountain, losing moisture as it continues downward. Therefore, the opposite side of the mountain gets very little rain. This slows down the water cycle. But, when the moist air from the oceans move up the mountain range, the air cools causing the water vapor to condense and eventually fall back to the Earth as rain or snow. So, as you can see, the water cycle works in conjunction with the temperature, pressure, and topography of the land.