The TV weather man happened to mention this rule of thumb the other day so I looked it up.
This is a good post.
when forecasting the overnight low temperature, it should never be more than a degree or two cooler than the dewpoint temperature.
Latent heat of course.
From the post.
This is why warm, moist air is so important when looking at the formation of thunderstorms. The heat capacity of water is pretty incredible, and it provides that extra fuel that makes storms so violent.
Speaking of rules of thumb, some of us have heard; hot to cold ventilate bold, cold to hot ventilate not.
One of my long-time chief mates had never heard this, he lived in Florida so I told him if we were gong from Florida to Maine we needed to get rid of the bad Florida air and replace with good Maine air and if we had good Maine air in the holds we needed to keep it.
Condensation on a car ship is bad news, the water doesn’t hurt the cars but the various debris carried does, soot from diesel exhaust, dirt, paint chips, rust etc.
We learned that our assumptions on what the humidity of the air in the holds was not reliable so when there was a possibility of moisture in the hold being a problem we sent the cadet around in the morning with sling psychrometer. Having the wet/dry temps from each deck was a big assist. We had been at times ventilating and making things worse. To measure is to know.