Water Water

Our Blue PlanetOur Blue Planet

Introduction Introduction

• Covers three-quarters of the earth surface

• All living things need water to survive.

• Water exists in three different states:- Solid- Liquid- Gaseous

Water in Solid State Water in Solid State

ice snow hail

Water in the Liquid StateWater in the Liquid State

• Most of the Earth’s water is sea water.

raindrops

dew clouds

Water in Gaseous StateWater in Gaseous State

Water vapour Steam

Similarities:

•Both are colourless

•Both are water in gaseous state

Differences

At any temperature

1000C

Changing States of Water: Changing States of Water: Heat GainedHeat Gained

• Solid to liquid: Melting (00C)• Liquid to Gaseous : Evaporation

: Boiling (1000C)

Changing States of Water: Changing States of Water: Heat LossHeat Loss

• Liquid to Solid: Freezing (00C)• Gaseous to Liquid : Condensation

Changing States of Water: Changing States of Water: Heat LossHeat Loss

• Liquid to Solid: Freezing (00C)• Liquid to Gaseous : Condensation

MeltingMelting• From solid to liquid• Gains heat• Happens at 00C • Ice to water• Temperature stays the same• Heat gained to change state of water

from solid to liquid• State of water during melting: solid and

liquid

Freezing Freezing

• From liquid to solid• Heat loss from water to the surrounding• Happens at 00C • Water to Ice• Temperature stays the same

Boiling Boiling • From liquid to gaseous• Gains Heat• Happens at 1000C • Water to Steam• Temperature stays the same• Heat gained to change state of water

from liquid to gaseous• State of water: liquid and gaseous

Evaporation Evaporation

• From liquid to gaseous• Gains heat• Evaporation happens all the time and at any

temperature. • Water to Water Vapour

Condensation Condensation

• From gaseous to liquid• Loses heat• Condensation happens due to temperature

difference• Water Vapour to Water • Steam to Water

Condensation Condensation

(1000C)

(100C)

(1000C)

(700C)

Faster Slower

More water droplets

Less water droplets

Evaporation Evaporation

• The rate of evaporation depends on a few factors:- Presence of wind- Humidity - Temperature- Area of exposed surface

Presence of Wind Presence of Wind

• Water evaporates faster in the presence of wind.

• When water evaporates, water vapour gathers above the surface of the water.

• Wind will carry the water vapour away, making space for more water to rise.

Humidity Humidity (Amount of water vapour in the (Amount of water vapour in the

air)air)• High humidity: Large amount of water

vapour in the air

• Higher humidity Slower rate of evaporation

• There is little or no space in the air for any more water vapour when humidity is high.

Temperature Temperature

• Higher temperature Faster rate of evaporation

Area of Exposed SurfaceArea of Exposed Surface

• The larger the area of the exposed surface, the greater the amount of evaporation.

Larger exposed surface area

Smaller exposed surface area

Area of Exposed SurfaceArea of Exposed Surface

0 fold 1fold 2 folds

Increase rate of evaporation

Video on processes of water

Water Cycle Video 1

Water CycleWater Cycle

• Respiration– Animals give out water vapour

Stage 1:• Evaporation

– Heat from sun evaporate water from rivers, lakes and sea

• Transpiration– Plants give out water vapour through

stomata of leaves

Water CycleWater CycleStage 2:• Condensation

– Water vapour rises into the air and condenses into water droplets

Water CycleWater CycleStage 3:• Precipitation

– Clouds become to heavy and fall as rain to the ground

Water CycleWater Cycle

Main source of energy for water cycle

Water Cycle Song: Processes

Water Cycle Song