Weather Patterns During The Ice Ages

What about weather patterns during the ice ages? If the temperature dropped dramatically and the earth's ice cover increased, it would certainly change the weather patterns that we are familiar with today.

I have noticed how we can take a look into the weather patterns during the ice ages just by looking at a map.

The Rhone Valley is wide and broad and runs north-south across southeastern France between the Massif Central and the Alps. The valley is parallel to the French-Italian border and extends from the city of Dijon through Lyon to Marseilles on the Mediterranean coast.

The Mistral is the wind which passes through the Rhone Valley from the north. The wind can, at times affect lands across the sea such as Sardinia and even north Africa. You can read more about the Mistral if you wish by going to http://www.wikipedia.org/ and entering in "Mistral (wind)".

My hypothesis is that the Mistral must have been far more powerful during the ice ages than it is today, and that gives us a clue as to the weather patterns as a whole during the ice ages.

Let's briefly review the formation of glaciers during the ice ages. Glaciers begin to build when the temperature drops low enough so that the snow of one winter has not completely melted when snow begins to fall the following winter. This means that snow continues to pile up, year after year and century after century.

Snow is compacted into ice by the weight of the snow above it. Eventually, a vast and thick sheet of ice has formed that is wide enough to be affected by the rotation of the earth. The ice sheet is pulled southward, toward the equator, and along with the eastward rotation of the earth. (For more on this, see "New Discoveries Concerning Glaciers" on the glacier blog). All the while, the white snow and reflective ice contributes to the cooling spiral by reflecting solar energy back into space instead of absorbing it.

In the posting "Mountains And Glaciers" on this blog, I explained how glaciers can form much further south than they ordinarily would at ground level if there are mountains with sufficient altitude that can provide a suitable site for glacier formation.

Now, let's go across the Mediterranean Sea from the Rhone Valley to the mountains of Algeria. Here is a map link, http://www.maps.google.com/ , or you can follow along in a physical geography world atlas.

South of the city of Algiers, there is a lake in the Atlas Mountains. The name of the lake in Arabic is Chott El Hodna. Moving south and east, to the south of the mountain range on lower ground is Chott Melrhir, Chott El Gharsa, Chott Jerid and, Chott Fejaj.

This line of lakes extends from northwest to southeast, just what we would expect if the lakes were formed by glacial movement out of the mountains and guided by the earth's rotation, and end at the Golfe de Gabes on the east coast of Tunisia. The directional alignment of the string of lakes clearly shows this glacial movement and the Golfe de Gabes also appears as an outlet of this glacial movement to the sea.

Notice that Chott El Hodna, in the mountains south of Algiers, is on a straight line with the Rhone Valley if it were extended across the Mediterranean Sea. There must have been very heavy snowfall in the Altas Mountains to form the glaciers which carved this string of lakes. Since the area is mostly dry today, other than these lakes, my conclusion is that the Mistral was much more powerful and consistent during the ice ages than it is today.

Now, let's go far away, to Buffalo, NY. The thing that made me think of this scenario is the lake-effect snow that Buffalo is known for during the winter. The prevailing wind in the area is from the west, so that it sweeps across the length of Lake Erie before arriving at Buffalo. When the lake is warm but the air passing over it is cold, it picks up more water than it can hold.

When the air reaches the eastern end of the lake and passes over land, which loses heat faster than water and so is colder, the air becomes unable to hold the water vapor (vapour) that it has collected. The result is all-too-familiar to residents of the area, tons and tons of snow dropped on Buffalo and the Southern Tier of New York State, down to around the Pennsylvania state line.

Lake Erie is the shallowest of the Great Lakes, and the only one that freezes over, and when it does the lake-effect snow ceases because the ice covering the lake prevents further evaporation. There is actually more snowfall in central New York State than there is is Buffalo because they get their lake-effect snow from Lake Ontario, which is too deep to freeze over during the winter.

The basin of the Mediterranean Sea is too deep, and too far south, to freeze over during the ice ages. A similar phenomenon to Buffalo's lake-effect snow happened here during the ice ages. The powerful, cold Mistral passed over the warmer sea. It picked up a lot of water until it reached the Atlas Mountains, south of Algiers.

Altitude was also a factor here, higher and thinner air can hold less water. A vast amount of snow was dropped in the mountains. This snow formed the glaciers, which were moved by the rotation of the earth to form the string of lakes that we can see on the map today.