water cycle

1. The Water Cycle
•To understand the processes involved in the
water cycle

2. What is Evaporation?
•It is the process of a liquid heating to form a
gas

3. What is
Condensation?
•It is the process of a gas cooling to form a
liquid

4. The Water Cycle
Water is constantly moving between sea, air and land
The sun shines and
the sea is heated
heat

5. The Water Cycle
Water is constantly moving between sea, air and land
Evaporation
The water
evaporates and
forms clouds

6. The Water Cycle
Water is constantly moving between sea, air and land
Condensation
As air rises it cools
and condenses. It
reaches the
ground as rain,
snow, sleet or hail.

7. The Water Cycle
Water is constantly moving between sea, air and land
The snow
melts and
flows
Lakes
form
Snow forms

8. The Water Cycle is complete

9. What is
humidity ?

10. Humidity
It is the amount of water vapor in the air .
The higher the temperature the more water
vapor it can hold
Warm air can absorb much more water vapor
than cold air

11. Relative Humidity
The amount of water vapor in the air compared to the
total amount that air can hold at that temperature .
When water can’t hold water vapor anymore the relative
humidity is 100%

12. • When the air is saturated or filled with water vapor
,any additional water vapor will condenses in to a
liquid ….This temperature is called “Dew point “

13. Types of Clouds
1)Stratus
Blanket Like

14. 2)Cumulus
• Billowy puffy clouds that seem to rise from flat bottoms

15. 3)Cirrus
• They are wispy feather like .

16. Naming clouds
• we can call the clouds according to their altitude by
adding prefix or suffix.
Example:
Prefix “Cirro “ Clouds formed at high altitude
“Alto “ Middle altitude
“Nimbo” They are clouds bringing thunder
storm
Suffix Nimbus They are clouds bringing
thunder storm

17. Alto stratus Prefix
Cumulo nimbus Suffix
Examples

18. Cloud Cover

19. Types of cloud

20. Types of precipitation
1)Rain
It falls when the temperature is warm .

21. 2) Sleet
• Forms when raindrops freeze and turn into pellets of ice before falling
to earth’s surface.

22. Snow
• It falls when the air becomes cold that water vapor becomes solid rather than condensing
into droplets

23. Hail stones
• As wind pushes raindrops high into the atmosphere where they turn
into ice.

24. • The process repeat as water freezes in layers and the
hail stone grow.

25. Clouds and weather
•Puffy cumulus cloud They often appear
in fair weather .

26. •Wispy cirrus cloud Change in
weather is happening

27. Darker stratus
Forecast
Precipitation
Nimbocumulus

28. Large Cumulus Clouds
• Heavy rain or snow showers which ends quickly.

29. Stratus cloud
• Long lasting precipitation with smaller raindrops and snow
flakes

30. Measuring amount of rainfall
• People have measured rainfall for thousands of years.
• It is especially important for farmers to know how much
rain will fall this year.
• The instrument used to measure rain fall is called “Rain
Gauge”

31. Thunderstorm
• It begins when intense heat causes air to rise quickly (low
dense air )
• This heated air ,or updraft, then cools and forms clouds.

32. • Updrafts hold water droplets and ice crystals in the cloud.
• When they grow too heavy for the updrafts to support , they fall
as rain or hail.

33. • As the precipitation falls many of the raindrops and ice
crystals collide (hit each other) .
• Downdrafts in the cloud also cause falling air to brush
against rising air .
• This results in the formation of electric charge at the bottom
of the cloud .
• (Negative electric charges build up in the bottom of the
cloud.)

34. • When enough of a charge builds up ,it produces a huge
spark ,which is called “lightning “ .
• Lightning superheats the air around it ,where air expands
suddenly (spread out ) then contracts as it cools.
• This rapid movement of air produces sound waves that are
heard as “thunder “

35. Tornado
• It is a violently rotating column of air that extends
downward from thunderclouds and touches the
ground.

36. • A tornado starts when moist hot air mixes with cold dry air .
• On hot days ,rising air (low density) causes powerful updrafts .
• The air begins to spin in the cloud ,if the updraft is strong air
rushes with high speed decreasing the pressure at the center.
• As more air rushes in ,the air pressure at the center decreases
more and more ,increasing the spinning speed .
• Soon a funnel forms that may reach the ground

38. • The swirling funnel starts to descend.
• The wind speed in the tornado can reach 500km/hr or
more.

39. • The force of the tornado ‘s winds destroy houses ,
cars and anything in its path.

40. Hurricane
It is a large ,rotating tropical storm
system with wind speeds of at least
119km/hr

41. What is a hurricane?
A hurricane is a very destructive and dangerous
storm. It forms in stages. The hurricanes are filled
with rain, strong winds, lightning, thunder, hail
and tornadoes.
Stages of the hurricane :
1)Tropical depression
2)Tropical storm
3)Hurricane (wind speed 120km/hr)

43. • It starts as thunderstorm over the ocean near the equator .
• The heat causes air above the ocean to be warm with low pressure
,and evaporation of the water (area of tropical depression)
• As the water vapor rises up , the temperature decreases causing it
condensation and release of energy causing the warming of air that
causes the decrease in density more and more.
• AS the air pressure falls ,the wind grow stronger when winds near the
center reach 120km/hr the storm is considered hurricane .
• Hurricanes produce huge amount of rain .

44. What is eye of a hurricane?
While some hurricanes, are
small, others can be quite
large. Hurricanes are mighty
storms.
In the center of a hurricane
is an eye. Ironically, the eye
is actually a calm area in a
hurricane.