Why Lakes Don’t Have Tides?

Have you ever been to a beach and just stood there, admiring the scenery, without a worry in the world? It’s truly an experience to relish. There is a truly magical feeling in the crashing waves that bring extreme peace to humans.

It was at a moment like this when a thought came to me: can lakes have tides too?

Let’s take a plunge into this idea and see where we come up for air…

waves

Credits:Vaclav Mach/Shutterstock

How Are Waves Formed?

Before we make a decision on the ‘tide-producing capacity’ of lakes, we should first understand how waves are formed. Gravity is the most important force that creates tides. In 1687, Sir Isaac Newton explained that ocean tides result from the gravitational attraction of the Sun and moon on Earth’s oceans.

If you’ve ever spent 24 hours on a beach, you will have noticed that the shoreline changes (sometimes drastically) in that relatively short span of time. This shift is caused by the forces of gravitation, which are constantly at play. The force pulls the water up and tides are formed.

Does This Apply to Lakes Too?

Theoretically, yes, it does. In fact, this tidal pull applies to everything – even land masses! That might sound crazy, but it’s true, so technically, lakes should also produce tides. However, in reality, they don’t.

Waves on Rocks

Gravitational Forces at Play (Credits:ChrisVanLennepPhoto/Shutterstock)

This is because, in the end, it all comes down to relative sizes.

Because of the small size of lakes, they contain very small volumes of water. Also lakes are self-contained, unlike oceans, which are interconnected. Due to these factors, the level of displacement of water in a lake is quite small. According to the NOAA (National Oceanic and Atmospheric Administration), the most powerful spring tides in the Great Lakes of North America (which combined contain over 20 percent of all the world’s freshwater) amount to a mere five centimeters (two inches) at the most.

Therefore, in smaller bodies of water, the tides are simply too small for us to notice.

But I’ve Definitely Seen a Tide in a Lake!

People sometimes say that they have also seen tides in lakes, but there is an explanation behind that. There is something that is often mistaken for tidal movement, which is called a seiche (pronounced saysh), or a standing wave, which can reach several meters in height. Let’s have a look at this phenomenon:

Seiche (black coloured wave)

Seiche (black-colored wave)

Seiches are caused when very strong winds and changes in atmospheric pressure push water from one end of a body of water to the other. When the wind stops, the water naturally rebounds to the other side of the enclosed area. The water then continues to oscillate back and forth for hours or even days. Thus, it appears to be a full-fledged tide, which is likely what you’ve seen in the past.

If you have ever observed water sloshing back and forth in a swimming pool, bathtub, or even a cup of tea, then you have witnessed a small-scale seiche. On a much grander scale, however, the same phenomenon occurs in large bodies of water, such as bays and lakes.

This is why a seiche appears to resemble a tide in a lake, but this effect has nothing to do with the moon’s delicate dance with our oceans.

References

  1. The Guardian
  2. Do The Great Lakes Have Tides? – National Oceanic and Atmospheric Administration
  3. How It Works Daily
The short URL of the present article is: http://sciabc.us/9yofq
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About the Author:

Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spends a lot of time watching movies, and an awful lot more time discussing them. He likes Harry Potter and the Avengers, and obsesses over how thoroughly Science dictates every aspect of life… in this universe, at least.

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