Cold Water Bottle Also Sweats

Have you ever wondered or had a thought about why the closed bottles which contain the cold water or cold drinks sweat?  Have you asked  where the water comes from?

Actually the fact is that neither the bottle sweats nor the water comes from the inside of the bottle. The water is from the outside atmosphere.


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The atmospheric air always contains some water in the gaseous state (water has three phases i.e. Solid phase – ice, Liquid phase – water, Gaseous state – vapour). When the water is in the gaseous state mingled with the atmosperic air we can not see it. So we may think the air in the atmosphere do not have water. But it is wrong. The atmospheric air always has some or more water according to its temperature. When the air is in high temperature the moisture (water vapour in the air in gaseous state) content will be greater which means air can hold  more moisture content. When the temperature of the air is low the moisture content, the air can hold, is also low.

High temperature air – more moisture content (more water in the invisible gaseous state)

Low temperature air – less moisture content (less water in the invisible gaseous state)

When the air is cooled it cannot withstand the moisture any more in the gaseous state and it gives water in the liquid state. Technically, we say air condenses the water from the invisible gaseous state to visible liquid state.

Air at high temperature + more moisture content


Air at low temperature + water + less moisture content

The air surrounding the bottle gets cooled by the cold drink. When the air at outside is cooled it cannot hold more moisture. So some moisture condenses and becomes water. This water stays the outside of the bottle and makes us to think the bottle sweats.

Terms Used:

  1. Atmospheric air: The air on the surface of the earth.
  2. Moisture: The water contains in the air as gaseous phase (invisible) .
  3. Phase: The state of a substance. Generally solid, liquid, gas.
  4. Vapour: Any liquid in the gaseous phase. (For water it has a specific name called steam usually with hot)
  5. Condensation: The conversion of a substance from the gaseous state to liquid state is called condensation.

Water  →      

Solid state         –   ice      – visible,

Liquid state       –  water   – visible,

Gaseous state  –  Vapour – invisible.

The outside atmospheric air always contains some water in the invisible state (Gaseous State).When the cool drink or water bottle cools the outside air, the outside air gives some water in the visible state (Liquid State). The water from the outside air stays at the outside of the bottle and looks like the bottle sweats.

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