I’ve never been there, but from what I understand, London gets foggy on the reg. But why? What causes fog? And what about London makes it so susceptible to this weather pattern? This simple demonstration will help you explain to kids (and/or whoever else cares to pay attention) why foggy London town is so bloody foggy.
Like A Jar of Clouds
Just a handful of items are needed for this experiment. One: a large jar, preferably glass; two: a strainer; three: hot water (the hotter the better, but not boiling); and, four: a bunch of ice cubes.
First, fill the jar to the top with hot water. Let it sit for a minute or two, then pour out most of the water, leaving an inch or so at the bottom. Put the strainer over the mouth of the jar, and put your ice cubes in the strainer.
In no time flat, your jar will be filled with fog thicker than pea soup. If your jar is filled with actual pea soup, you may have followed the instructions incorrectly.
It’s the Water Cycle, Y’alls!
So, just how did hot water and ice cubes create fog? Well, the cold coming off the ice cubes caused the warm, moist air inside the jar (courtesy of the hot water) to condense. The air becomes saturated—that is, it has a relative humidity of 100 percent, or very close to it.
In real life, one of the ways fog is created is when warm, moist air travels over land or water that is much cooler than it is; it can also happen when warm, moist air meets another, cooler air mass. London is not far from the English Channel, which regularly causes warm, moist air to move over the considerably cooler land mass, leading to fog.
Humid air turning to fog, which is a type of water vapor, can in turn lead to further condensation (like the water droplets on the outside of a cold soda can on a hot day) or actual rain. Water shifting from one form to another and precipitating back onto land—be it as condensation or rain—is an important part of the water cycle.