Why is a lot of "sweating" on the wall of tap water pipes a sign of rain in summer?

First of all, I understand a truth: when the temperature of water vapor in the air is lower than itself, it will condense into small water droplets. Second, understand that the water temperature in the tap water pipe must be much lower than the outside air temperature in summer, resulting in the pipe wall being lower than the surrounding air temperature. Thirdly, before it rains in summer, the humidity in the air increases obviously, so there will be a lot of water droplets on the outer wall of the tap water pipe when it rains in summer.

In summer, a lot of "sweating" on the wall of tap water pipes is often a sign of rain. If there is a lot of "sweating" on the pipe wall, it means that the water vapor content in the air is high and the humidity is high, which is a precursor to rain. The "sweating" of water pipes is not the water leakage in the pipes, but the water pipes are mostly buried underground and the water temperature is low. When the water vapor in the air contacts the pipeline, it will release heat and liquefy into small water droplets attached to the outer wall. In summer, the weather is sultry, the temperature is high, and there is much water vapor in the air; The groundwater temperature in the water pipe is low, so is the temperature of the water pipe. Water vapor with higher temperature condenses on the surface of the water pipe to form small water droplets, which is the liquefaction phenomenon of water vapor, and the heat should be released;

Sweating of water pipes is mainly due to the fact that the water vapor in the outside air is heavy and the temperature of tap water is lower than the natural temperature, which leads to the condensation of water vapor into water droplets on the water pipes, thus forming a daily sweating phenomenon.

You can wrap a layer of insulation material on the tap water pipe, such as foam plastic insulation pipe, asbestos insulation layer, or cloth and other materials with poor thermal conductivity.

In summer, sometimes the weather is sultry, the temperature is high, and there is more water vapor in the air; The groundwater temperature in the water pipe is low, so is the temperature of the water pipe. The high-temperature steam releases heat on the surface of the water pipe to form small water droplets, which is the liquefaction phenomenon of water vapor. There is water vapor in the air, so we can't see it. The tap water pipe is cold, and the water vapor in the air liquefies into water droplets when it is cold, and adheres to the water pipe, so we can see this phenomenon.