How water vapour is present in air at room temperature

Replies

• 

  rahul69

  gdchethan

  we say humidity that is water content in air ..... that is water in vapour stage in air .......my question is how water can be in vapour state at room temperature

  Some molecules ( which are at the surface of ,say a glass of water), may randomly take away energy of neighboring molecules due to collisions, and may escape as water vapor.😘, this is how I think it happens.
• 

  gdchethan

  yeah water evaporates thats right but how can water remain at vapor state at room temperature
• 

  Whats In Name

  Evaporation is different from boiling.It occurs at any temperature until our environment reaches saturation.Water from Oceans,rivers (etc) and even clouds continuously evaporates and thus vapours in atmosphere.Concept of evaporation is already explained by #-Link-Snipped-#
• 

  Ramani Aswath

  A substance can be in one or more of three states - solid, liquid and vapour at any given temperature. There is one point called triple point at which all three states can be in equilibrium.
  Temperature is a measure of the average kinetic energy of molecules. In any large collection of molecules there will be some molecules that have a high kinetic energy. When this is more than the cohesive force between molecules in the solid or liquid states such molecules can escape into the gas phase.
  
  If ice is kept in a closed container at a temperature below 0 degC, some molecules escape and be a vapour without any liquid water being there!
  
  If you check your fridge you will notice that vegetables dry up if left open long.
  
  Incidentally that is how freeze drying is done.