Is it possible to say water vapour and dew is the same? I know that the water vapour is the gaseous phase of water. But what is the dew? I just wonder how can I categorised it. Is it the liquid or the gas phase of the water.

Figure below shows dew formed in grass. It seems as a liquid. But is it actually exhibit in liquid phase or gas phase?

enter image description here

  • $\begingroup$ @ santiago : Why the question falls to "off-topic" when I ask for opinions? $\endgroup$ Commented Jun 22, 2015 at 9:20
  • $\begingroup$ @Onthewaytosuccess 'primarily opinion based' is a close reason, the information states Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. - but, as I mentioned, it is now on topic and has great answers. $\endgroup$
    – user15489
    Commented Jun 22, 2015 at 9:42
  • 4
    $\begingroup$ Why would you think it's not a liquid? $\endgroup$
    – OrangeDog
    Commented Jun 22, 2015 at 10:07

2 Answers 2


Let's have a look at the definitions of dew:

dew (the free dictionary)

  1. Water droplets condensed from the air, usually at night, onto cool surfaces.
  2. Something moist, fresh, pure, or renewing: "The timely dew of sleep / ... inclines / Our eye-lids" (John Milton).
  3. Moisture, as in the form of tears or perspiration, that appears in small drops.

Therefore dew is water in the condensed phase, i.e. liquid. Water vapour on the other hand is the gaseous phase. They are definitely not the same.

  • $\begingroup$ Then what is the connection between water vapour and dew? $\endgroup$ Commented Jun 22, 2015 at 9:33
  • 2
    $\begingroup$ Water changes its state of aggregation from gaseous (vapour) to liquid (drops, dew), that process is called condensation. $\endgroup$ Commented Jun 22, 2015 at 9:39
  • $\begingroup$ Can I take it as latent heat of vapourization? $\endgroup$ Commented Jun 22, 2015 at 9:45
  • $\begingroup$ @Onthewaytosuccess I don't understand this question. $\endgroup$ Commented Jun 22, 2015 at 9:59
  • $\begingroup$ I mean the heat produce in the process that you just mention above as latent heat of vapourization? $\endgroup$ Commented Jun 22, 2015 at 10:01

As dew is condensed water vapour [1] and condensation is the change of matter from gas phase to liquid phase [2] dew is clearly liquid water.

So on the one hand they are somehow the same as they both consist of water but on the other hand they are not the same as they are water in different states of matter.


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