2. IntroductionIntroduction
Evaporation is the change of state in a substance fromEvaporation is the change of state in a substance from
a liquid to a gas. In meteorology, the substance wea liquid to a gas. In meteorology, the substance we
are concerned about the most is water. Forare concerned about the most is water. For
evaporation to take place, energy is required. Theevaporation to take place, energy is required. The
energy can come from any source; the sun, theenergy can come from any source; the sun, the
atmosphere, the earth, or objects on the earth such asatmosphere, the earth, or objects on the earth such as
humans.humans.
3. During EvaporationDuring Evaporation
• Water turns from a liquid to a gas.Water turns from a liquid to a gas.
• Water moves from rivers and lakes into theWater moves from rivers and lakes into the
atmosphere in the form of water vapor.atmosphere in the form of water vapor.
• Water vapor forms clouds.Water vapor forms clouds.
• Water changes into solid.Water changes into solid.
4. Factors InfluencingFactors Influencing
EvaporationEvaporation
• Wind speedWind speed: the higher the wind speed, the: the higher the wind speed, the
more evaporationmore evaporation
• TemperatureTemperature: the higher the temperature, the: the higher the temperature, the
more evaporationmore evaporation
• HumidityHumidity: the lower the humidity, the more: the lower the humidity, the more
evaporationevaporation
5. Fog – Clouds On TheFog – Clouds On The
GroundGround
There is absolutely no difference betweenThere is absolutely no difference between
fog, and clouds found high in the air. Fogfog, and clouds found high in the air. Fog
is simply a cloud that has formed near theis simply a cloud that has formed near the
surface of the Earth. There are four mainsurface of the Earth. There are four main
types of fog, radiation fog, advection fog,types of fog, radiation fog, advection fog,
upslope fog, and evaporation fog.upslope fog, and evaporation fog.
6. How does evaporation causeHow does evaporation cause
cooling?cooling?
• In an open vessel the liquid keeps onIn an open vessel the liquid keeps on
evaporating. The particles of liquidevaporating. The particles of liquid
absorb heat energy from theabsorb heat energy from the
surrounding to regain the energy lost insurrounding to regain the energy lost in
the evaporation. This absorption ofthe evaporation. This absorption of
energy from the surroundings make theenergy from the surroundings make the
liquid cool.liquid cool.
8. Latent heatLatent heat
• When an object is heated, the heat energyWhen an object is heated, the heat energy
of the object gets hidden into the contentsof the object gets hidden into the contents
of the beaker. This process is known asof the beaker. This process is known as
latent heat.latent heat.
• To come into the gaseous form, the liquidTo come into the gaseous form, the liquid
takes extra heat from the contents of thetakes extra heat from the contents of the
beaker in the form of Latent Heat Ofbeaker in the form of Latent Heat Of
Vaporisation.Vaporisation.
10. Cooling of a Deodrant onCooling of a Deodrant on
handhand
• When perfume is put on our palm, it feelsWhen perfume is put on our palm, it feels
cold because the particles of matter gaincold because the particles of matter gain
energy from our surroundings or from ourenergy from our surroundings or from our
palm and evaporate at a fast rate causingpalm and evaporate at a fast rate causing
our palm to feel cold.our palm to feel cold.
11. Water kept in an earthen potWater kept in an earthen pot
• Water kept in an earthen pot becomesWater kept in an earthen pot becomes
cool after some time because of the tinycool after some time because of the tiny
holes present in the pot, which helps theholes present in the pot, which helps the
water to evaporate. And due to this thewater to evaporate. And due to this the
water becomes cool in a short period ofwater becomes cool in a short period of
time .time .