When does sun evaporation stop in the uk?

[zaax]

Sometime in the autumn the sun is so low that evaporation by the sun stops in the uk.

When is this date?

[*Stormforce~beka*]

Interesting question! ...

[Coopsy]

I would have thought it would continue all year? As water can evaporate in warmer or colder conditions, otherwise puddles wouldn’t dry up lol. 

Plus sublimation occurs during winter when snow evaporates. Slightly different though as thats a solid to gas rather than liquid to gas. 

[Ross90]

It's reduced quite noticeably in the winter but it never stops completely. 

[MetCat]

Seems like around this time of year. Ground is almost perma-damp til about late March most years.

[richie3846]

It isn't possible to seperate out temperature, wind, sunshine and humidity. When talking about pure evaporation off a surface, all these factors will play a part, as will the surface itself. On a winter's day with the sun out, we can expect the pavement to be dry where the sun shines, but on long grass, it'll be wet all day.

 

[Mapantz]

It depends on what the OP is directly asking.. Evaporation in the meteorological sense doesn't stop, it's called the water cycle.

[richie3846]

7 minutes ago, Mapantz said:

It depends on what the OP is directly asking.. Evaporation in the meteorological sense doesn't stop, it's called the water cycle.

Evapotranspiration isn't in the original question, but of course is a vital part of the equation also. 

[Mapantz]

3 minutes ago, richie3846 said:

Evapotranspiration isn't in the original question, but of course is a vital part of the equation also. 

Talking of which, since recording evapotranspiration on my station, I have never recorded zero.

[richie3846]

4 minutes ago, Mapantz said:

Talking of which, since recording evapotranspiration on my station, I have never recorded zero.

That is really interesting because I assumed that on a day in January with freezing fog all day and temps of -1, it would be zero

Edited October 21, 2022 by richie3846
Typo

[Eagle Eye]

10 hours ago, zaax said:

Sometime in the autumn the sun is so low that evaporation by the sun stops in the uk.

When is this date?

It's the energy technically that causes the evaporation, hotter substances have more energy so will evaporate easier than colder substances but unless they are absolute freezing they still have some some energy and sublimation can still occur.

[Mapantz]

11 minutes ago, richie3846 said:

That is really interesting because I assumed that on a day in January with freezing fog all day and temps of -1, it would be zero

Ice days are pretty rare here, with the last one on January 7th 2021. No sunshine recorded, not sure about fog, but still managed 0.2mm.

I haven't looked at my evap data for a long time, but just noticed it is at 768.73mm for the year. While my rainfall total is 488.6mm. You can certainly see why water sources got very low.

Edited October 21, 2022 by Mapantz

[richie3846]

13 minutes ago, Mapantz said:

Ice days are pretty rare here, with the last one on January 7th 2021. No sunshine recorded, not sure about fog, but still managed 0.2mm.

I haven't looked at my evap data for a long time, but just noticed it is at 768.73mm for the year. While my rainfall total is 488.6mm. You can certainly see why water sources got very low.

Yes I've been trying to make sense of all this, in this drought year. What I've observed 'on the ground' is that trees suck the moisture out of the ground more severely then grass. This can be observed by dead grass near trees (even with reasonable light levels) and sunken clay soils where trees grow. My observations suggest that evapotranspiration calculations are highly subjective and not very accurate.

[Scuba steve]

It doesn’t reduced yes 

 

[Earthshine]

So long as relative humidity is below 100%, evaporation will occur.  Same with the sublimation of ice and snow.