How does a bathtub drain in Australia?
I am off for a two week foray down-under and I am pretty excited to discover Australia and to witness, first hand, how my hotel room's bathtub will drain. This is not nearly as weird as it sounds! Apparently, bathtubs drain counter-clockwise in the Northern hemisphere, and clockwise in the Southern hemisphere. Many people believe that the bathwater's rotation is due to the Coriolis Effect. This effect is defined as "the apparent acceleration of a moving body on or near the Earth as a result of the Earth's rotation" in the Encyclopaedia Britannica. In such a way, the rotation of the earth appears to deflect the path of a moving mass, such as air or water. In fact, weather systems are very strongly affected by the Coriolis Effect. In satellite pictures of clouds at the North Pole, the clouds swirl to the right. Pictures of clouds at the South Pole show clouds swirling to the left. Cyclones are also under the Coriolis Effect, with those in the Southern hemisphere rotating clockwise, and those in the Northern hemisphere rotating counter-clockwise. Despite the fact that many people think the Coriolis Effect is occurring in their bathtub, scientists argue that the Coriolis Effect impacts only on the path of large objects and that the way the bathwater drains is due more to the shape of the drain than the location of the tub on earth. In a carefully controlled environment, however, with a perfectly round and smooth tub and with water that has been left to stand for several days to eliminate all turbulence, water drained through a single hole at the bottom of this perfect tub would, indeed, be affected by the Coriolis effect. So, I will scrub out the bathtub in my hotel room, let the water stand for days, and then watch it drain... or maybe I will go snorkelling instead!
Answered By: Dr. Christine
Can can learn more about about this by watching the video: The Truth about Toilet Swirl-Southern Hemisphere on CurioCity