# Why Lake Tahoe Doesn't Fully Freeze

• PhysicsinCalifornia
In summary, the conversation discusses why Lake Tahoe does not completely freeze over, even when the temperature above the water is below 4 degrees Celsius. The reason is that ice is a good insulator and forms on the top of the water, preventing the cold temperature from reaching the bottom of the lake. However, given suitable heat transfer conditions, the whole lake can freeze over. The conversation also mentions that the Earth's underground temperature plays a role in preventing the lake from freezing solid.
PhysicsinCalifornia
This is a physical intuition problem I don't quite understand fully.

The question is, why doesn't Lake Tahoe freeze (the whole Lake)?

I know the crystal structure for water breaks at 4 C and the volume is at its lowest point at that temperature.

If the temperature above the water is less than 4 C(say -11 C), why doesn't the whole lake freeze up?

Ice is a good insulator. The water at 4C therefore can't lose heat very well through the ice layer. As it does lose heat, the ice gets thicker, increasing the insulation.

That is exactly why fish can swim around under the ice and they don't solidify.

The whole lake doesn't freeze up because ice floats. The ice forms on the top of the water and not on the bottom. Then as AB said, it insulates the water underneath it.

It is to my understanding that the whole lake WILL freeze up when the whole lake turns to 4 degrees celcius.

If this is true, I don't understand it(lol)

I understand that the ice will be the insulator for the lake, so the outside temp. will not directly reach the bottom of the lake instantly.(Maximum depth for Lake Tahoe is 501 meters, or 1645 ft., this is the second deepest in the US!)

So given a length of time, the whole lake will freeze up?(and turn into a glacier like the one that hit Titanic?)

Or does the bottom of the lake stay at a higher temperature because there is higher temperature down there, or closer to the Earth's center?

or am I just thinking too much over my head here?

Given suitable heat transfer conditions the whole thing will freeze up, happens typically and commonly to ponds etc. all the time.

Last edited by a moderator:
PhysicsinCalifornia said:
So given a length of time, the whole lake will freeze up?(and turn into a glacier like the one that hit Titanic?)
Remember, the Earth itself is warm underground, a constant temp of about 55 F once you are a certain depth underground (then rising as you go deeper). So the cold from above has to fight and overcome the warm from below to freeze a pond solid. It can happen, but it doesn't very often.

Sorry, just noticed this thread is 4 years old...locked.

## Why doesn't Lake Tahoe fully freeze during winter?

There are several factors that contribute to Lake Tahoe not fully freezing during winter. One major factor is the depth of the lake, which averages at about 1,000 feet. This depth allows for the water to remain insulated and not freeze completely. Additionally, the lake's large surface area and constant movement from wind and currents also prevent it from freezing over.

## Does the water temperature play a role in Lake Tahoe not freezing?

Yes, the water temperature plays a significant role in the lake not freezing. Lake Tahoe's water temperature remains relatively constant throughout the year, usually ranging from 40-50 degrees Fahrenheit. This temperature is too warm for the lake to freeze entirely, even during the coldest winter months.

## Are there any human-made factors that contribute to Lake Tahoe not freezing?

Yes, human-made factors such as urbanization and development around the lake can also contribute to it not freezing. The runoff from roads, buildings, and other structures can add salt and other chemicals to the water, lowering its freezing point. This makes it even more difficult for the lake to freeze.

## Has Lake Tahoe always not fully frozen during winter?

No, there have been instances in the past where Lake Tahoe has frozen over completely. However, these instances are rare and usually only occur during extremely cold winters. The last time the lake fully froze was in 2011, and before that, it was in 2007.

## Are there any benefits to Lake Tahoe not fully freezing?

Yes, there are several benefits to the lake not freezing over entirely. It allows for year-round recreational activities such as boating, fishing, and swimming. It also helps to maintain a healthy ecosystem for the diverse plant and animal life that call Lake Tahoe home.

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