Cumulus Support

when the temperature outside goes up the humidity goes down (I understand that), but the indoor humidity stays almost constant over temperature changes? - bar boiling pans at meal time when it rises slightly.

My indoor humidity reading is nearly always between 60 - 70 %.

Good question. Yours is a bit higher than mine which seems to be approx. 35% - 45%, but hey how accurate are our measuring equipment? I guess (and it is a guess!).

When the house is colder overnight there is also less activity likely to generate moisture i.e. people are asleep so we breathe out less moisture, no showers or cooking etc. So, even though it’s colder the relative humidity remains fairly stable and of course the reverse is true during the day.

Just a thought

Mark, I am not too sure where you are going with the statement...

Presently, the outside temperature is 9.6°C (49.2°F) and the outside humidity is 91% - the inside temperature is 22.5°C (72.5°F) and the inside humidity is 42% - the computer room (office) temperature and humidity is regulated through the use of a heat pump.

Mark,

I know exactly what you mean, the nearest I have to any sort of idea is that it could be about the sort of screen you might have, especially if it's the stock one. My thought is that direct sunlight on it perhaps causes it to heat up and any moisture providing the humidity local to the sensor is possibly evaporated away more vigorously, and that could lead to the lower humidity in that immediate area.

However this is probably not really a feature indoors I'd imagine, and if it were, then it'd quite possibly void your warranty.

'Tis only my best guess so far of course.

Relative Humidity is calculated on the ability of the air to hold moisture.
The warmer the air, the more moisture it can hold. The cooler the air, the less moisture it can hold.
Therefore, the Relative Humidity will increase as the temperature drops and the air cools. Assuming no additional moisture is added to the air, the cooling air will appear to be more humid.
If the temperature drops below the point where the air cannot hold any more moisture, you will get condensation.
I hesitate to call it the dew point when referring to indoor temperatures and humidity.
Carl

Flying Eye wrote:Mark,

I know exactly what you mean, the nearest I have to any sort of idea is that it could be about the sort of screen you might have, especially if it's the stock one. My thought is that direct sunlight on it perhaps causes it to heat up and any moisture providing the humidity local to the sensor is possibly evaporated away more vigorously, and that could lead to the lower humidity in that immediate area.

However this is probably not really a feature indoors I'd imagine, and if it were, then it'd quite possibly void your warranty.

'Tis only my best guess so far of course.

It may have an effect. But I will add that my outdoor unit receives no direct light and is actually covered by a 4m x 10m varandah that is insulated. Even though it gets no direct light, purely on the fact we go through a "dry" season, my unit will reach it's maximum minimum on 10% humidity. The inside humidy fluctuates at the same time, but just to a lesser degree. We also have all our windows open. No heater (ha ha, that's funny where I am). However, when we put the aircon on the changes in the inside humidity a dramatic.