Evaporation Question

[TwoHedWlf]

In the winter a trick is to have higher humidity air. That way less evaporation from our skin so we lose less body heat and feel warmer. ( The problem in a closed house in winter is we can have too much moisture if we have warm tank water plus showers, cooking as such. I run my dehumidifier at about half capacity and also have a humidity gauge so I can try to keep it about 50 to 60%.)

The other trick in the winter is to keep the humidity as low as possible The lower the humidity the less energy it takes to heat the air. If you're sweating then your house is too hot. anyway. Here it takes a lot of work to get the humidity down to 50-60%, most of the time it's naturally up around 80+% inside over winter.

 

[skjl47]

The other trick in the winter is to keep the humidity as low as possible The lower the humidity the less energy it takes to heat the air. If you're sweating then your house is too hot. anyway. Here it takes a lot of work to get the humidity down to 50-60%, most of the time it's naturally up around 80+% inside over winter.

Hello; That is new to me. Can't say I have ever thought of or seen any thing about how humidity levels affect the amount of energy to heat air. Not something I am aware of. I would like to know the mechanism involved.

The effect humidity has on the "feel" of the air is something I have seen published. We people are bags of water at a fairly high temperature. We always have some moisture on our skin. We do not have to be sweating like a pig for the effect. With dry (low humidity) air some of that moisture evaporates off our skin more quickly and since the evaporation takes energy from our body we tend to feel cooler. In high humidity air the evaporation rate is slower so less energy is removed from our body. That is the way it has been explained to me.

On what use to be a more typical winter day around here the air temperature would be low and would not have the energy to hold much moisture. Very low humidity most of the time. Not so much that way so far this winter. My area just ended the wettest year on record ever since records have been kept. Only a couple of cold spells so far with temps low enough for snow.

 

[TwoHedWlf]

Hello; That is new to me. Can't say I have ever thought of or seen any thing about how humidity levels affect the amount of energy to heat air. Not something I am aware of. I would like to know the mechanism involved.

The more water in the air the higher the specific heat, due to water having a significantly higher specific heat than air. Every winter we're barraged by "Home heating tips" and the top tip is that dry air is easier to heat.

The effect humidity has on the "feel" of the air is something I have seen published. We people are bags of water at a fairly high temperature. We always have some moisture on our skin. We do not have to be sweating like a pig for the effect. With dry (low humidity) air some of that moisture evaporates off our skin more quickly and since the evaporation takes energy from our body we tend to feel cooler. In high humidity air the evaporation rate is slower so less energy is removed from our body. That is the way it has been explained to me.

That's the opposite of what I've seen published and experienced, and evaporation is insignificant in cool weather. The heat transfer is more through conduction straight to the air. Cool humid air absorbs heat quicker from any warm surface than dry. At the same temperature cold dry air absorbs heat much more slowly and is far more comfortable than cold damp air.

On what use to be a more typical winter day around here the air temperature would be low and would not have the energy to hold much moisture. Very low humidity most of the time. Not so much that way so far this winter. My area just ended the wettest year on record ever since records have been kept. Only a couple of cold spells so far with temps low enough for snow.

I think your definition of high humidity from the sounds of it is dryer than our low humidity. It's not uncommon over winter to have temps of 1-2°C and 90+% humidity outside. Inside when my dehumidifier is off the humidity usually settles around 75-80% and around 19-20°C Actually, it's a hot dry day today, no rain in a week and looks like the humidity has barely dropped under 60%

 

[FINWIN]

When I was cycling my 225 I discovered if I left the glass lids open I would lose a gallon a day to evaporation. Temp was at 81 for cycling and I was running large air disks with 3 hobs and internal filters...so surface agitation speeded up the process further. Made the room warm and humid too.

 

[skjl47]

The more water in the air the higher the specific heat, due to water having a significantly higher specific heat than air. Every winter we're barraged by "Home heating tips" and the top tip is that dry air is easier to heat.

Hello; Again this is something I have not heard of.

That's the opposite of what I've seen published and experienced, and evaporation is insignificant in cool weather. The heat transfer is more through conduction straight to the air. Cool humid air absorbs heat quicker from any warm surface than dry. At the same temperature cold dry air absorbs heat much more slowly and is far more comfortable than cold damp air.

Hello; Pretty sure some of this is not correct.

uncommon over winter to have temps of 1-2°C and 90+% humidity outside

Hello; This does not sound right.

 

[Fishflyer]

Hello; I have raised chickens with my family as a child and also used an incubator in my science classes.
Back in the day it was fairly easy to find eggs that would hatch. I would get a number of eggs of about the same age. My students would crack open an egg each day to chart the development of an embryo. Yes the incubator had a bit of water and a light bulb heat source. We also had to hand turn the eggs as I recall.

Hello, Yes respectfully aware of egg turning. This is too prevent embryo from sticking to eggshell wall. Raised chickens also. Hens did the egg turning. Mostly we wanted the eggs, but we would put any fertile egg under Bantam hens and they would hatch and raise the chicks. Humidity is, as you know of course to keep the embryo from drying out. My incubator has a handy egg turning motor and arm, but yes I have done it manually with my old Incubator.

 

[TwoHedWlf]

Hello; This does not sound right.

What does not sound right about a fact?

Just a quick check of a local weather station's archive for August 2015:

Maximum temperature 6.8 °C on day 10 at time 13:41
Minimum temperature 1.1 °C on day 10 at time 08:38
Maximum humidity 91 % on day 10 at time 09:07
Minimum humidity 73 % on day 10 at time 16:33

 

[skjl47]

What does not sound right about a fact?

Just a quick check of a local weather station's archive for August 2015:

Maximum temperature 6.8 °C on day 10 at time 13:41
Minimum temperature 1.1 °C on day 10 at time 08:38
Maximum humidity 91 % on day 10 at time 09:07
Minimum humidity 73 % on day 10 at time 16:33

Hello; Looks like I am wrong. Thought about it for a few minutes and I guess this is the relationship having to do with relative humidity (RH). If I recall correctly relative humidity is a measure of the amount of water vapor the air actually holds compared to what it could hold at a particular temperature. So if a volume of air at a particular temperature can hold 10 units of water vapor and it actually holds 9 units then it is at 90% relative humidity.

We use to measure RH with a device having two thermometers. One thermometer having a bare bulb and the other having some cotton fabric covering the bulb. Dip the fabric in some distilled water and sling the two thermometers around in the air. Check the measured temperature difference between the two and the difference can give the RH.

I also do not think in degrees C and did not do the math. 6.8 and 1.1 are both above freezing in Celsius.

Anyway good catch on your part.

 

[The Morning]

Quick update. I was away for the past 4 days and returned to find water levels virtually the same as when I left. This leads me to believe that my issues may be stemming from the combination of the plastic strip being removed coupled with the fireplace running. Obviously with me being gone the fireplace was not on. I would guess that the fireplace pulls a good bit of water from the tank, something I wasn’t seeing when the strips were in place.

 

[Fishflyer]

Hmmm interesting. Comparing that to a campfire outside drawing oxygen on a humid night or even a mildly raining night, the fire will still pull in humid air and dry surrounding area, (ie wet clothes).
Stands to reason a fireplace would have a drying, evaporation effect in a contained area.