BrainPop

What is the water cycle?The continuous movement of water from

water sources into the air, onto and over land, into the ground, and back to the water sources.

6 stepsPrecipitationInfiltrationRunoffTranspirationEvaporationCondensation

PrecipitationOccurs when rain, snow, sleet, or hail falls

from the clouds onto the Earth’s surface.

It is the primary connection in the water cycle that provides for the delivery of atmospheric water to the Earth.

Most precipitation falls as rain.

InfiltrationThe downward movement of water from the

land surface onto soil or porous rock.

Water can be filtered and cleaned as it passes through the soil or rock.

RunoffIs water, usually from precipitation, that

flows across land and collects in rivers, streams, and eventually the ocean.

TranspirationThe process by which plants release water

vapor into the air through their leaves.

Transpiration accounts for approximately 10% of all evaporating water.

EvaporationOccurs when liquid water changes into water

vapor.

Approximately 80% of all evaporation is from the oceans.

Evaporation is more intense in the presence of warmer temperatures.

CondensationOccurs when water vapor cools and changes

back into liquid droplets.

This is how clouds form.

Water vapor needs a place to condense on.GrassA glass

Dew PointThe dew point is the temperature to which

air must cool to be completely saturated.

Relative HumidityHumidity: is the amount of water vapor or

moisture in the air.

Relative Humidity: is the amount of moisture the air contains compared with the maximum amount it can hold at a particular temperature.

When air holds all of the water it can at a given temperature it is said to be saturated.

The higher temperature, the more water the air can hold.

Relative HumidityHow to calculate relative humidity:

Actual water in the air x 100 = relative humiditySaturated air (full)

Suppose that 1 m³ of air at a certain temperature can hold 24 g of water vapor. However, you know that the air actually contains 18 g of water vapor. Calculate the relative humidity.

Example: 18 g/m³ x 100 = 75% 24 g/m³