1. The Three Forms of Water
Water is unique! It exists naturally in three states, defined by how they shape, flow, and spread.
| Property | Solid (Ice) | Liquid (Water) | Gas (Vapour) |
|---|---|---|---|
| Shape | Fixed shape | Takes container shape | No fixed shape |
| Flows? | No | Flows easily | Flows & diffuses |
| Spreading | Does not spread | Spreads on clean surface | Spreads everywhere |
2. Phase Transitions
Changing states requires adding energy (heating) or removing energy (cooling):
HEATING
Melting & Evaporation
COOLING
Freezing & Condensation
3. Evaporation Variables
Evaporation happens continuously at room temperature. But how can we make it go FASTER?
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Exposed Surface Area: Bigger surface = faster rate. (e.g., Water evaporates faster from a flat plate than a bottle cap)
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Temperature (Sunlight): High heat boosts molecular speed. (e.g., Wet clothes dry quicker on a sunny day than in shade)
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Air Movement (Wind): Strong winds blow away moist air. (e.g., Running a fan helps damp clothes dry inside)
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Humidity (Air Moisture): If air already has high moisture, evaporation slows down. (e.g., Rainy days are highly humid → clothes dry slowly)
4. Condensation & Clouds
When invisible water vapour hits a cold surface, it turns back into liquid droplets.
Why does cold water make glasses sweat?
The container is not leaking! Moisture present in the ambient air touches the cold glass wall, cools down, and condenses into visible water droplets.
How Clouds Form:
- Warm air containing lighter water vapour rises up.
- As it moves higher, the atmosphere gets colder.
- The vapour cools and condenses around tiny dust particles.
- These droplets float together, forming clouds. When they get too heavy, they fall as rain, hail, or snow!
5. The Cooling Effect
Evaporation absorbs thermal energy from its surroundings, leaving things colder! This is nature's own air conditioner.
Water slowly seeps through tiny pores of the clay and evaporates outside, cooling the drinking water stored inside.
Rubbing alcohol or sweat evaporates rapidly from your skin, absorbing body heat and giving you an instant icy, cool sensation.
Using a nested double-pot setup separated by wet sand, we can store vegetables fresh for days without electricity!
6. The Water Cycle
The continuous, life-giving process that circulates water between the earth's surface and atmosphere.
Ocean and land water absorbs solar heat, rising up as vapour.
Vapour cools high up to form clouds around dust particulates.
Droplets aggregate, getting heavy enough to fall as rain, hail, or snow.
Water runs back into lakes, rivers, oceans, and groundwater aquifers.