11 ms·

People get this idea that northern US must be at a high latitude just because it is cold in winter, and it simply isn't true. The 49th parallel roughly matches

People get this idea that northern US must be at a high latitude just because it is cold in winter, and it simply isn't true. The 49th parallel roughly matches the latitude of Paris, London, Brussels, Munich, Prague or Vienna. The problem isn't that you won't get enough sunlight if you lay down naked in the sun, the problem is that you can't because it is too cold.

mrcarrot 3y ago
None of those places are especially sunny in the winter though!
- david-gpu 3y ago
  But Canada is! And that is what the comment I replied was talking about.
  - ben7799 3y ago
    There is pretty much no place in Canada at all that doesn't have a total blackout of availability of Vitamin D from sunlight in the winter. All the northernmost US states have a period of insufficient sunlight/angle to produce Vitamin D, and basically all of Canada is north of that. Maybe there's an island that is Canadian territory that is south of say New York or San Francisco that I don't know about of course.
ben7799 3y ago
No the problem is the sun has to hit the earth's atmosphere at a certain angle in order for the correct wavelengths of light to pass through the earth's atmosphere. The amount of Vitamin D your body can generate from sunlight is based on your skin tone, where you are, the time of day, the day of the year, and the angle of the sun at that time and place. Above/Below a certain latitude (N/S) there is a window of time where the sun never hits that angle at any point during the day, so you could sit outside naked all day long and still get zero vitamin D. If this seems counterintuitive consider if you keep going far enough away from the equator and get into the arctic/antarctic the winter has no sunlight at all, and you clearly can't produce Vitamin D from sunlight if the sun never rises.
- dghughes 3y ago
  Yes that study (I can't recall the name of it) also noted the angle of the sun and limited daylight hours. Plus winter clothing means most often the only exposed skin is your face or even just half your face if you have a scarf on. My city in Canada about 46.2 degrees north and about 300km from the eastern Maine border. Here in winter it gets light at 8am and dark at 4pm if there are no clouds. So most people are at work they go to work in the dark and leave when it is dark.

mrcarrot 3y ago

None of those places are especially sunny in the winter though!

david-gpu 3y ago
But Canada is! And that is what the comment I replied was talking about.
- ben7799 3y ago
  There is pretty much no place in Canada at all that doesn't have a total blackout of availability of Vitamin D from sunlight in the winter. All the northernmost US states have a period of insufficient sunlight/angle to produce Vitamin D, and basically all of Canada is north of that. Maybe there's an island that is Canadian territory that is south of say New York or San Francisco that I don't know about of course.

ben7799 3y ago

No the problem is the sun has to hit the earth's atmosphere at a certain angle in order for the correct wavelengths of light to pass through the earth's atmosphere. The amount of Vitamin D your body can generate from sunlight is based on your skin tone, where you are, the time of day, the day of the year, and the angle of the sun at that time and place. Above/Below a certain latitude (N/S) there is a window of time where the sun never hits that angle at any point during the day, so you could sit outside naked all day long and still get zero vitamin D. If this seems counterintuitive consider if you keep going far enough away from the equator and get into the arctic/antarctic the winter has no sunlight at all, and you clearly can't produce Vitamin D from sunlight if the sun never rises.

dghughes 3y ago
Yes that study (I can't recall the name of it) also noted the angle of the sun and limited daylight hours. Plus winter clothing means most often the only exposed skin is your face or even just half your face if you have a scarf on. My city in Canada about 46.2 degrees north and about 300km from the eastern Maine border. Here in winter it gets light at 8am and dark at 4pm if there are no clouds. So most people are at work they go to work in the dark and leave when it is dark.