Water becomes ice when its molecules move slowly enough to create stiff connections. Normally, the molecules in the waterfall move in response to both flow and thermal agitation. However, if it gets cold enough, the heat impact is so minimal that not even the waterfall’s motion can prevent ice from forming, initially gently but then very rapidly.
Is it the bottom of the waterfall that freezes rather than the top?
The waterfall freezes at both ends, as well as in the middle. This process can be impacted by the falls’ individual terrain, since fragile ice can attach to icy rocks or cliff edges under certain conditions. The ice then acts as an anchor, allowing more ice to form as water flows over it.
Often, it appears to form at the top and then drags down like an icicle. You’ll notice a small collection of ice at the bottom and top, and ultimately, especially if there’s a rock base or cliff behind it, that will help connect it to how cold the rock is.
The waterfall will not freeze until the water source that feeds it does first. And the size of the water source is a crucial factor to consider. Niagara falls will never freeze. However, it can become chilly enough to freeze the mist it produces, resulting in some stunning ice sculptures.
However, under certain conditions, the water’s surface can freeze, causing ice to build around the falls and on the rocks, creating the impression that Niagara has stopped. For such an event to occur and Niagara Falls to partially freeze, certain weather conditions must coincide. To achieve significant freezing, temperatures must fall far below freezing and remaining there for an extended amount of time. For significant freezing to occur, the mercury must usually be kept at or below 14°F (-10°C) for several days or weeks.
Niagara Falls, formed around 12,000 years ago at the end of the last Ice Age, was sculpted by melting glaciers. The water from the Great Lakes began to flow over the Niagara Escarpment, a steep cliff of old granite that progressively eroded the bedrock, creating the valley and the three renowned waterfalls: Horseshoe Falls, American Falls, and Bridal Veil Falls.
Contrary to popular belief, Niagara Falls does not freeze entirely. Water freezes at 32°F (0°C), but due to its sheer volume and mobility, it would require temperatures much lower—around 14°F (-10°C) or colder—for an extended length of time. With around 168,000 cubic meters of water (the equivalent of one million bathtubs) flowing per minute. This immense force and volume makes the flow far too strong to solidify entirely.
Even as portions of Niagara freeze, the water beneath the falls continues to flow. In most situations, the water beneath the ice flows steadily, as the river’s steady movement keeps it from freezing altogether. The rush of water from the falls also stirs the river, preventing it from getting too still for ice to entirely take control.
However, during extremely severe winters, huge layers of ice can accumulate on the river’s surface, forming a “ice bridge.” This phenomena has been observed to extend over the river, connecting the Canadian and American sides. Historically, these bridges were so solid that people could walk over them on foot.
In fact, up until 1912, tourists were permitted to walk across these ice bridges, occasionally putting up kiosks and even participating in sports on the frozen river. However, after a terrible incident in which the ice collapsed, the practice was prohibited.
Content for this question contributed by Pamela Serena, resident of Taunton, Bristol County, Massachussets, USA
