Steam rising in forrests on cold days?

:slight_smile: Often I see on very cold days that what looks like steam rising from the trees in a forrest after a rain storm.
How is this as? The temperature seems far too cold for condensation.

Perhaps you’re seeing fog?

Condensation occurs as the temperature drops. I think you are confused about “steam” vs. clouds/fog.

Given a certain amount of humidity, fog is likely when the temperature is 4° or less above the dewpoint.

When the earth, or the trees, or whatever, are at a higher temperature than the atmosphere, they’ll warm a small layer of air around themselves, and any moisture on them will equilibrate with that layer. When convection or wind moves that moist layer into the surrounding cold air, some of the water will condense, giving fog.

Forest floors have a lot of leaf/needle litter and such. So there’s quite a bit of natural composting going on. This makes the litter layer a bit warm and, if moist enough, some vapor is given off due to the heat. Doesn’t take much to cause a fog.

It doesn’t have to be particularly cool for this to happen either. In the tropics, you regularly see mist rising from the forest immediately after a rainstorm.

Here in Washington I used to watch trees steaming after a rain - but only from the side that the sun was heating.

If you are talking about a general could of steam rising… It is because the ground / trees are still hot and the rain is being evaporated. Since it had been raining, the humidity is already pretty high so this evaporating vapor will most likely cause the air to reach 100% relative humidity and immediately condense into a visible steam.

Also, if you are looking a one single smoke stream rising from a mountainside, it is most likey that there is a cave there.

It might be helpful to recognize that there are several different meanings for the word “steam.”

From Merriam-Webster:

1 : a vapor arising from a heated substance
2 a : the invisible vapor into which water is converted when heated to the boiling point b : the mist formed by the condensation on cooling of water vapor
3 a : water vapor kept under pressure so as to supply energy for heating, cooking, or mechanical work; also : the power so generated b : active force : POWER, MOMENTUM <got there under his own steam> <sales began to pick up steam>; also : normal force <at full steam> c : pent-up emotional tension <needed to let off a little steam>
4 a : STEAMER 2a b : travel by or a trip in a steamer

I think the OP may be confusing senses 2a or 3a, which refer to the invisible water vapor that rises from water when it is heated to the boiling point, with sense 2b, which refers to the visible mist composed of tiny water droplets (not water vapor) that condenses when air containing water vapor is cooled. This latter phenomenon can occur over a wide range of temperatures.