1. Jassem al Majed abdulAziz al hashash Fawaz al enezi Abdullah bahzad
Most clouds form as air rises and cools/water falls to earth’s surface as precipitation
Jassem al Majed
abdulAziz al hashash
Fawaz al enezi
Abdullah bahzad

2. vocabulary Evaporation Condensation Precipitation Humidity Saturation
Relative humidity
Dew point
Cirrus
Cumulus
Stratus
Fog
Freezing rain
Sleet
Hail
Acid Rain

3. Temperature effect water in the air
Water is always in the atmosphere , you may see water in solid form.
Evaporation : is the process by which a liquid changes into a gas.
For water to evaporate it needs extra energy.
Condensation : is the process by which a gas such as water vapor changes into a liquid.
Condensation occurs when moist air cools.
The picture on the top right shows the process of evaporation and condensation at work.
How it works is water in the teakettle absorbs heat, then it gets enough energy to evaporate into water vapor.

4. Water in the air
Vast amounts of Earths water are recycled , the ocean hold most of the water.
Any type of liquid or solid water that falls Earths surface is called precipitation.
Water vapor can also condense on solid surfaces.
As you can see on the top right it is a water cycle.
First : water evaporates from bodies of water.
Second : water vapor condenses to from clouds.
Third : water falls Earth’s surface as precipitation.

5. Humidity and relative humidity
On a warm summer day , evaporation of moisture from your skin can help you feel comfortable.
However, a lot of water vapor in the air can cause less moisture to evaporate from your skin.
Humidity: is the amount of water in air.
Humidity varies from place to place and from time to time.
Saturation: a condition in which the rates of evaporation and condensation are equal.
In unsaturated air or vapor more water evaporates into the water.
In saturated air or vapor the amount of water that evaporates equals the amount that condenses.
The amount of water vapor in air at saturation depends on the temperature of the air .
Relative humidity : compares the amount of water vapor in air with the maximum amount of water vapor that can be present at that temperature.
Dew point: is the temperature at which air with a given amount of water vapor will reach saturation.

6. Characteristics of clouds
Cirrus
Cumulus
Stratus

7. Cirrus clouds
Cirrus: means curl of hair. Cirrus clouds appear feathery or wispy.
Cirrus clouds form in very cold air at high altitude, made of ice crystals, they have a wispy or feathery appearance.

8. Cumulus clouds
Cumulus means heap or pile. Cumulus type clouds can grow to be very tall.
Cumulus clouds are puffy white clouds with darker bases, they look like cotton balls floating in the sky.

9. Stratus clouds
Stratus means spread out. Stratus type clouds form in flat layers.
Stratus clouds form in layers when air cools over a large area without rising or when the air is gently lifted.

10. Fog
Fog is a cloud that rests on the ground or a body of water. It usually forms when a surface is colder then the air above it.
Fog can look beautiful rolling over hills or partly covering structures such as bridges. However, it ften makes transportation dangerous by limiting visibility,

11. Cloud types Cirrus Cirrocumulus Cumulonimbus Altocumulus Cirrostratus
Altostratus
Nimbostratus
Cumulus
Stratus

12. Precipitation forms from water droplets/ice crystals
All precipitation comes from cloud.
Example rain occurs when water droplets in the cloud fall to the ground.
One way the precipitation can form is through the combining of cloud droplets.
How it works is the tiny droplets of water move up and down in clouds, as the droplets continue to combine they grow larger and larger , eventually they become heavy enough to fall.
It takes about a million droplets to make a single raindrop.
Another way that precipitation can form is through the growth of ice crystals.

13. Measuring precipitation
Scientist use a rain gauge to measure rainfall,
A funnel or opening at the top of the gauge allows rain to flow into the cylinder,
By measuring the water collected you can find out how much rain fell in a storm or over a period of time.

14. Type of precipitation
Precipitation reaches Earth’s surface in various forms, some precipitations freezes or melts as it falls through the atmosphere.
1. Rain and Drizzle : form from water droplets or ice crystals that melt as they fall.
2. Freezing Rain: is rain that freezes when it hits the ground or other surfaces.
3. Sleet: is rain that freezes into ice pellets while falling through cold air.
4. Snow: forms from ice crystals that merge in clouds.
5. Hail: forms when ice pellets moves up and down in clouds, growing larger as they gain layers of ice.

15. Precipitation can carry pollution
Rain water is naturally a little acidic.
Acid rain: is rain that has become more acidic than normal because of population.
Ex. Factories, power plants, automobiles, and some natural sources release sulfur dioxide and nitrogen oxides into the air.
Acid rain harms trees and raises the acidity of lakes.