A child holding an umbrella walks amid heavy rainfall in New Delhi on July 9, 2024.
| Photo Credit: Arun Sankar/AFP
Q: After I take a hot shower and the hot, wet air from the bathroom combines with the cold air from the hall, why doesn’t it rain in my house?
A: It probably does. Your house may not be big enough to contain an air mass capable of producing a long shower of rain, but depending on the size, temperature, and relative humidities of areas in your house and the amount of wet air, you are probably getting at least a trace of rain-like precipitation.
Look closely at your bathroom walls after your shower; often there will be beads of water on them that did not result from direct contact with the shower stream. This is most noticeable on your ‘foggy’ mirror. A raindrop or two may even fall on your head from the ceiling.
Like rain outside, this precipitation results from condensation of water vapour, where the warmer air meets a mass of colder air (a cold front) or, more commonly, when warm damp air touches cold walls. The resulting ‘sweating’ walls are a common problem in damp climates and anywhere that a basement contains air that is wetter and warmer than its walls. And in the days before frost-free refrigerators, ‘snow’ built up into glaciers in the freezer compartment for the same reason.
To fight sweating walls, dehumidifiers and ventilators will help, especially an outside vent for the warm wet air from the clothes dryer.
