1. When water at different temperatures is mixed the combined system of water comes at an intermediate temperature.
2. This is what happens when cold water is poured in hot water.
3. The temperature of hot water is close to boiling point of water so there are more vapours of water above this steam.
4. When cold water is poured suddenly in this hot water system,vapours first come in contact with cold water and they condense.
4. However due to presence of vapours just above hot water surface they float and we see intense vapours containing condensed water.