Your mom's approach was based on a concept known as evaporative cooling. Evaporation is a process in which water absorbs heat from its surroundings, resulting in a cooling effect. When water evaporates, it takes energy (in the form of heat) from its surroundings, which lowers the temperature of the environment.
Filling a bathtub with cold water on a hot day can potentially help cool down your house through evaporative cooling, but the effectiveness of this method depends on various factors such as humidity levels, ventilation, and insulation. Here's how it generally works:
Evaporative cooling: As the water in the bathtub evaporates, it absorbs heat from the air, lowering the ambient temperature in the room. This can make the immediate vicinity around the bathtub feel cooler.
Ventilation: For this method to be effective, you need proper ventilation in your home. Opening windows or using fans can help facilitate the movement of air and allow the humid air near the bathtub to be replaced with drier air from outside. This helps enhance the evaporative cooling effect.
Humidity: The effectiveness of evaporative cooling depends on the humidity levels in your area. Evaporative cooling works best in dry climates where the air can readily absorb moisture. In humid climates, the air is already saturated with moisture, making it less effective.
Insulation: The overall effectiveness of using a heat sink like a bathtub also depends on the insulation of your home. If your house is well-insulated, it can help maintain a cooler temperature by preventing heat from seeping inside.
While using a bathtub as a heat sink can provide some localized cooling, it may not significantly impact the overall temperature of your entire house. Other methods like using air conditioning, fans, shading windows, or employing energy-efficient cooling systems are generally more effective for cooling larger spaces.
It's worth noting that technology and energy-efficient cooling systems have advanced significantly since the time you were growing up, so there may be more efficient and effective methods available today.