Humidity and Temperature interaction?

Anyone here understand how the humidity and temps correlate.
I understand VPD but I am interested in like when you increase humidity does it lower the temp and vice versa
I noticed that when my humidity dropped to 58% the temperature increased from 79F to 81F.
When I turned the humidifier on in the grow tent, humidity went up to 65% and temperature went from 81F to 79F.
I think thats okay short term but would like to keep it under 80F and between 60-70% RH for mid late veg.

The environment outside the tent is consistent A/C is on in living room and I have a fan in front of the rooms door to blow the cool air into the room and the exhaust from the grow tent goes out through a sealed port i installed in the window.

Thanks

If you have a "space", a volume of air (your tent, etc), that is at a stable temp/RH, then we assume a fixed amount of water vapor in the air.. If you only change the temp, the following happens:
If temp goes up, but water vapor stay the same, RH goes Down. Recall that warmer air holds more water than cool, so the water vapor is using less of the capacity.
If the temp goes down, but water vapor stays the same, the RH goes up - because cooler air holds less water, so more of the capacity is used.

The main idea to keep is that warm air holds more water than cooler.

HTH, it could be explained further, but this is the basic of my understanding.

Your likely getting a swamp cooler or evaporative effect from your humidifier. Before AC they'd put blocks of ice in front of a fan to cool a room. It worked as long as you had the ice in front of the fan. After around 75-80° and around 60-70%rh they quit working and you'd just run a fan because at a certain point they're just adding humidity to the air. All of that was subjective to the user however. The downside is the more humiditiy in the air the longer the air can hold onto heat. Think walking on the beach at night. A few hours after sundown the beach is cool to walk on, walk into the water it'll be about the same temp it was during the day when the sand was too hot to walk on. Water, longer to heat up and holds the heat longer.

Modern AC's have a slight dehumidifiaction effect on your environment, condensation forms on the radiator coils the air is forced through in the air handler unit, that water is usually gravity drained outside the house somewhere. I've had a few places where the water is collected and pumped into the sewer lines. You do not want to have that pump break. That's how I learned all about AC condensation drains. Note: I'm not saying an AC is a dehumidifier, dehumidifiers remove much more water from the air than AC cooling coils. Life was a lot more humid before AC, my house as a kid had no AC and we lived a few miles from the Mississippi river. Over the summers our relative humdiity was whatever it was outside and at night we ran a dehumidifier.

There are three measures of humidity, absolute, relative, and specific.

Really briefly, specific humidity is the amount of wet air to dry air in an environment expressed as a ratio. Absolute humidity is the mass of water vapor divided by the mass of the air in an area. Relative humidity is the percentage of humidity in the air as it relates to the amount of vapor the air can hold at a that temperature and pressure. The ammount of water RELATIVE to the temperature of the air.

For relative humidity, if you think of the air as a glass that grows as it gets warmer it becomes easy to visualize. If the glass gets bigger but has the same amount of water, the percentage of water to volume of glass goes down. If the glass contracts as it gets cooler and the water stays the same, the percentage of water to glass increases until the glass shrinks so much it can't hold water and it spills.

As you lower ambient temperature the air can hold less water, so your RH goes up. Temps drop low enough (the dew point) the air can't hold water anymore and you get dew. As you raise the temp, the air can hold more water. So as long as the absolute humidity stays the same, the relative humidity will drop as the temp increases.

None of anything I wrote has anything to do with the plants. The first thing to think is your plants add humidity, they transpire putting more water in the air, it also evaporates out of your soil / medium / res. Then we come to VPD, which the Pulse chart is great but it doesn't account for mold points. I'll gladly sacrifice a little plant development to prevent mods and mildews. If anything my grow system needs me to slow veg growth as much as a possible anyway.

I've lived in a swamp most my life, so you guys adding humidity amazes me. I've got 2 dehumidifiers running to keep the house below 60%rh and the grow closet under 50% and my AC is fighting to keep the house at 75° and the flowers under 80°.