FL#4 The Hydrologic (Water) Cycle EcologyStandard 6D

The Earth's water is always in circulation. It has been recycled for the last 3 billion years. This process is called the water cycle.

Water is constantly being cycled through our environment, from the oceans to the atmosphere to the land and back to the oceans. Hence “cycle”.

Air is an important part of the water cycle. The hotter air is, the more water it holds. Hot air also rises. As air travels up the troposphere it is cooled and can no longer hold as much water and we get condensation. As air rises through the troposphere (first 6-8 miles) the temp can drop from 17 to -54 degrees Celsius. This cooling causes condensation.

Desert 128 o F Hot Air Rises Temp in the troposphere can go from 62 to –125 o F. Air Temp drops as air is forced over mountains. At Night Leeward Windward

Condensation Precipitation

Surface Runoff Subsurface Runoff Accumulation Evaporation Transpiration Condensation Precipatation Review

Water changes from liquid to gas via the process of EVAPORATION. Water can also enter the atmosphere as a gas via the process of TRANSPIRATION. This is when evaporation from the leaves of plants occurs.

Once water enters the atmosphere as water vapor, CONDENSATION (gas to liquid) can occur to form clouds. PRECIPITATION ( gas to liquid (rainfall, snow, etc.) can then occur.

When precipitation falls on the land it flows into streams, rivers, lakes, and groundwater. It is also absorbed by the roots of plants. Most water eventually ends up as RUN-OFF into the oceans or evaporating back into the atmosphere to continue the cycle over and over again.

1. What is the correct order of the water cycle? A. evaporation, precipitation, condensation, run-off B. evaporation, condensation, precipitation, run-off C. evaporation, run-off, condensation, precipitation D. none of these

2.Transpiration is… A. evaporation from lakes and rivers. B. formation of water droplets in clouds. C. evaporation from the leaves of plants. D. the absorption of water by the roots of plants.

3.Water changing from gas to liquid is called… A. evaporation B. condensation C. precipitation D. both b & c E. none of these

4. In the Water Cycle, which step immediately follows condensation? A.Evaporation B.Transpiration C.Precipitation D.Accumulation

5. What is this diagram showing? Water Cycle