Ok, whose idea was it to ride East to West? Everyone knows the prevailing wind in the US and Canada blows from the West towards the East... today we rode 58 miles against a 13 mph headwind... it was physically and mentally draining.
To understand why the wind blows towards the East, you have to be comfortable with two ideas: 1) Convection cells and 2) the Coriolis effect... First, convection: hot air rises and cold air sinks. You can see these rising and falling columns in a bowl of miso soup :-). At the Equator air, warmed by the direct sunlight, rises high in the atmosphere (which is about 10 miles high). As the air rises, nearby air is pulled to replace the rising column. This causes winds to travel along the surface of the Earth. At the poles, the air cools and sinks back to the ground. You could imaging a big conveyor belt with air travelling up at the equator, to the North at high altitude, down at the poles and then South across the surface. But in fact it's broken into three rotating cells of air: the Polar cell, the Ferrel cell and the Hadley cell:
The trick is to notice that, just like our gears in Day #5, the cells that touch each other rotate in different directions: if the Polar and Hadley cells rotate clockwise, then the Ferrel cell rotates counter-clockwise. The very key thing to notice is the Ferrel cell, which covers latitudes from 30 degrees to 60 degrees, has the ground winds travelling northward... we happen to live in the latitudes covered by the Ferrel cell. Ok, that all you need to know about convection cells. If this were the whole story, we would expect winds to travel across North America from South to North.
The Coriolis effect: we live on a sphere (more or less). A blob of air at the North pole is only moving in a tiny circle each day... a blob of air at the equator is moving at around 1,000 mph all the way around as the Earth rotates. If a Southerly blob moves Northward it will be faster than the new kids it rubs shoulders with, so it will move North AND Eastward, because it's so fast. BTW, this also applies to shells fired by battleships if they travel far enough North or South. That's why the prevailing wind in North America is towards the East, and today Mark and I felt it fighting us for 58 miles...
A maple frosted doughnut and a Cilantro Chicken wrap at Tim Horton's saved me:
Snapshot: 58 miles, starting at 6:45am and ending at 2:45pm, with 6.5 hours of actual riding:
When you say miso soup... Suddenly I can picture it! :) and I like picturing it as the blobs rubbing shoulders. -Nof
The wind theory needs more time to digest. I guess it’s the last full day riding on land of maple? Cannot wait to hear the stories of biking in the Midwest.