WATER CYCLE by Jaya : WATER CYCLE by Jaya
Water cycle : Water cycle Water is one of the basic building blocks of all life. It is also one of the basic ingredients of our weather. About 71% of the Earth's surface is covered by water. It is present in oceans, rivers, lakes, the polar ice caps, clouds, rain or snow, ground water and living things such as plants and animals.
Water cycle : Water cycle Water is always moving. Surface water, warmed by the sun, evaporates into the atmosphere. Water vapor is carried by the wind all over the globe. Eventually the water vapor cools and condenses into clouds, fog, dew or various forms of precipitation. Once on the ground the water can evaporate directly or travel as runoff into the ocean, rivers, lakes or a ground water system eventually to evaporate again. This dynamic pathway of water is called the water cycle.
WHAT IS EVAPORATION : WHAT IS EVAPORATION Evaporation
is the process of water turning from liquid into water vapor or steam. Water from rivers, streams, lakes, oceans, or even city streets evaporates and rises into the atmosphere, where it condenses.
This picture shows evaporation of water from a pond
WHAT IS CONDENSATION : WHAT IS CONDENSATION Condensation
is the opposite of evaporation: it is the process of water vapor in the air turning into liquid water. In the atmosphere, water vapor that has risen from the earth cools, condenses, and forms into clouds.
What are clouds : What are clouds Even though clouds are absent in a crystal clear blue sky, water is still present in the form of water vapor and droplets which are too small to be seen. Depending on meteorological conditions, water molecules will combine with tiny particles of dust, salt, and smoke in the air to form cloud droplets, which grow and develop into clouds, a form of water we can see. Cloud droplets can vary greatly in size, from 10 microns (millionths of a meter) to 1 millimeter (mm), and even as large as 5 mm. This process occurs higher in the sky where the air is cooler and more condensation occurs relative to evaporation. As water droplets combine with each other, and grow in size, clouds not only develop, but precipitation may also occur.
WHAT IS TRANSPIRATION : WHAT IS TRANSPIRATION Transpiration
is the process through which water that has been absorbed by plants becomes water vapor in the atmosphere. The water from the plant generally transpires from the pores of its leaves.
HOW TO BUILD A MODEL OF A WATER CYCLE : HOW TO BUILD A MODEL OF A WATER CYCLE Purpose
To identify the elements of the water cycle. To identify the sun as the source of power for the water cycle.
Materials
large, zip-lock plastic baggies
water
food coloring
masking tape
thermometer
PROCEDURE : PROCEDURE Put about a cup of water into the baggie.
Add a drop or two of food coloring.
Carefully seal the baggie and tape it onto a sunny window.
Hold the bulb of the thermometer against the bag for three minutes and then record the temperature.
Let the bag hang in the sun for a couple of hours then observe the bag again. Look for any changes in the bag. Hold the bulb of the thermometer against the bag again for three minutes. Has there been a change in temperature?
Will the temperature increase or decrease?
SELF STUDY : SELF STUDY Where did the tiny droplets of water on the side of the bag come from?
Hold a piece of colored ice against the condensed water vapor in the bag. This action should cause more water vapor to condense and precipitate down the sides of the bag.
Move the bag to a location where there is no sun. How does this new situation affect the water cycle?