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** This question is making the assumption that if a planet with a similar size and atmosphere of Earth is colder and has longer nights, it will have larger and more numerous glaciers. If this is not true, pretty much skip the rest of the question below. **

Imagine a planet pretty much identical to Earth, except for the day/night length and temperature. A full rotation of the planet takes about 16 Earth days. Additionally, during an ice age tens of millions years ago, the planet was significantly colder than Earth was at the same time.

Combining the longer nights and the colder temperatures, I'd assume glaciers would form in larger groups than they did on Earth. Not only that, but there would also be more groups of glaciers.

What I do not know, however, is what that would do the modern-day lakes. For example, the Great Lakes in North America were formed by retreating glaciers. In the case of this fictional, colder world, would those lakes be deeper? Would there be more Great Lakes because there are more glaciers?

What would the lakes of a planet with larger and more numerous glaciers look like?

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    $\begingroup$ Longer nights would not help glacier growth. Longer night adds nothing, but the inevitable longer day does increase melting. For glacier growth you want hot weather over the oceans, lifting moisture, which then falls as snow. And the snow must not melt , or at least must melt slower than the average snowfall rate. $\endgroup$ – PcMan Mar 29 at 18:46
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    $\begingroup$ What happened "millions of years ago" is utterly irrelevant. Most lakes are fragile and ephemeral structures, on geological time scales. Very few lakes endure for one million years (let alone several million), and those that do are of tectonic origin, not glacial. (For the specific examples of the North American Great Lakes: their basins are of tectonic origin, and were formed a very long time ago. The tectonic basins were scoured clean of sediment and were filled with meltwater to become lakes only yesterday, that is, about 10,000 years ago.) $\endgroup$ – AlexP Mar 29 at 18:52
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    $\begingroup$ P.S. Our own dear Earth was a planet of gigantic ice sheets only 12,000 years ago. We are currently living in a brief inter-glacial period in an ice age which started about 34 million years ago and is on-going. The climate of Earth is changing: it has always been changing and will always been changing. The point being that any planet suitable for life is probably like Earth in this respect; you can speak of a specific climate right now, but that is just an episode in an ever changing story. $\endgroup$ – AlexP Mar 29 at 18:59
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    $\begingroup$ @AlexP -- Except that this time around, we're going to beat the Ice Age and turn the entire planet into a permanent Venus within the next 75 years!!!! AAAAHHHHHHHHHHHHHHHHHHHHH!!!!!! $\endgroup$ – elemtilas Mar 29 at 20:26
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    $\begingroup$ @elemtilas: Mua-ha-ha-ha! (Plodding translation of a fragment from a Romanian poem: Venus, warm marble, sparking eyes of stone, arms soft like the thinking of a poet-emperor...) $\endgroup$ – AlexP Mar 29 at 20:51
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There would be bigger lakes in areas at lower latitudes.

Glaciers - yes, they dig lakes and yes they melt and fill lakes. All well and good. During the Ice Age, high latitude places that now have lakes would not have lakes, because there would be an ice sheet on top of them. Maybe there would be lakes underneath. It would be dark at those lakes and cottages would sell for cheap. You would have to duck while waterskiing.

Let us instead consider lakes that might exist in this cold world that would not exist if it were warmer. Western North America is dry now but it had big lakes in the glacier days. They were not because of glaciers. They were because it was cold. Lake Bonneville is a good example. It is now a lot smaller and is called the Great Salt Lake.

lake bonneville

https://en.wikipedia.org/wiki/Lake_Bonneville

Changes in global atmospheric circulation led to changes in the water budget of Lake Bonneville and other lakes in the Great Basin of western North America.[9][10][11] Mountain glaciers in the Bonneville drainage basin stored less than 5% of the water that Lake Bonneville held at its maximum,[12] so that even if all the mountain glaciers in the basin melted at once and the water flowed into the lake (this didn't happen—it took thousands of years for the mountain glaciers to melt, and Lake Bonneville was falling by that time), it would have had little effect on lake level. Lake Bonneville had no river connection with the huge North American ice sheets

Lake Bonneville was not a lake because of glaciers, but because of the same global climate that produced glaciers at higher latitudes. It was not alone - there were other big lakes in the west that are now little salt lakes or dried up completely.

I think equivalent dry lakes / salt lakes for Europe / Asia would be bodies of water like the Caspian and other central asian lakes, and the lakes that were once in North Africa where the Sahara is now. Like Lake Bonneville, these used to be bigger back when glaciers roamed the earth, slowly. If there are dry lakes or salt lakes in Europe proper I don't know of them but maybe AlexP will weigh in with examples.

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  • $\begingroup$ Almost all of Hungary (and parts of western Romania) is dried out sea... But that sea dried out about 1.8 million years ago, whereas lakes Bonneville and Palomas / Cabeza de Vaca etc. dried out in the recent past (geologically speaking). And if you allow artificially dried seas and lakes, then half the Netherlands sits on what was the bottom of the sea. If you allow re-filled dry lakes, then 5.5 million years ago the Mediterranean was the mother of all dry lake beds. $\endgroup$ – AlexP Mar 31 at 5:19
  • $\begingroup$ The Black Sea is a lake (of the same nature as the Caspian) which got reconnected with the ocean in the recent past (maybe about 9,000 years ago), about at the same time that Great Britain became an island. (The Black and the Caspian seas are remants of an ancient ocean, which became landlocked when the reckless driving of Africa produced the collision with Europe which raised the Pyrenees / Alps / Carpathians / Caucasus / Taurus mountain chains.) $\endgroup$ – AlexP Mar 31 at 5:19

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