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I was referring to an outdoor greenhouse, set up on a plot of land where a large garden was mentioned. Oriented in a north-south direction natural light is sti

by jrapdx3 12y ago

I was referring to an outdoor greenhouse, set up on a plot of land where a large garden was mentioned. Oriented in a north-south direction natural light is still plentiful even in winter, and supplementing with artificial light can be effective. You are right though, even a large south-facing window doesn't provide as much illumination as a proper greenhouse, sharply limiting what can be grown. BTW if you get 6 hours of daylight at 60 deg latitude, that's impressive. My location is ~46 deg, but because of surrounding hills, and frequent thick cloud cover, we effectively get barely 6 hours of daylight at the start of winter, maybe less. In the off season, we're relegated to getting what produce we can from the grocery store, taste-free as it may be...

exDM69 12y ago
> BTW if you get 6 hours of daylight at 60 deg latitude 6 hours was a guesstimate figure for when plants stop growing. That's for the actual lit period, not sunrise-sunset times. At the darkest period of the year, the sunrise is after 9am and sunset is somewhere around 3 pm. Looking at the exact figures, it's 5 hours 49 minutes on the shortest day of the year. If you work a regular day job, you'll never see the sun for several months. But effectively, that's pretty much perpetual darkness. During the midday, there's a brief period of "daylight", but most of the time is just twilight because the sun doesn't rise very high. The weather tends to be cloudy for the whole period, last year there was 20 minutes of unoccluded sunlight in December and one or two clear nights. You learn to manage with the darkness in the winter and the light in the summer but coping with the rapid change in spring/fall is the worst. Humans are photosensitive animals, it really fucks up your mind.
- jrapdx3 12y ago
  All of that sounds very familiar. Astronomical sunrise/sunset times aren't an accurate guide to actual perceieved day length. Topological obstructions, like nearby hills, and in our climate, overcast skies block or decrease sunlight penetration. Near my office, I've measured daytime illumination. At the least obstructed spot, midday it was 40K lux in the sunny summer, but late fall 9K was as good as it got when moderately cloudy. In late fall it's identifiably daylight (if barely) at 9:00 and getting dark by 15:00 even though sunrise/sunset times promise 8.75 daytime hours in early December. A couple of notable consequences are a high rate of seasonal depression, and widespread vitamin D insufficiency. Light is a cue for circadian rhythm, and people sensitive to fall/winter darkness often benefit with phototherapy. I'd make sure to take vitamin D supplements too, usually 2K IU is a standard recommendation.

by jrapdx3 12y ago

exDM69 12y ago

> BTW if you get 6 hours of daylight at 60 deg latitude 6 hours was a guesstimate figure for when plants stop growing. That's for the actual lit period, not sunrise-sunset times. At the darkest period of the year, the sunrise is after 9am and sunset is somewhere around 3 pm. Looking at the exact figures, it's 5 hours 49 minutes on the shortest day of the year. If you work a regular day job, you'll never see the sun for several months. But effectively, that's pretty much perpetual darkness. During the midday, there's a brief period of "daylight", but most of the time is just twilight because the sun doesn't rise very high. The weather tends to be cloudy for the whole period, last year there was 20 minutes of unoccluded sunlight in December and one or two clear nights. You learn to manage with the darkness in the winter and the light in the summer but coping with the rapid change in spring/fall is the worst. Humans are photosensitive animals, it really fucks up your mind.

jrapdx3 12y ago
All of that sounds very familiar. Astronomical sunrise/sunset times aren't an accurate guide to actual perceieved day length. Topological obstructions, like nearby hills, and in our climate, overcast skies block or decrease sunlight penetration. Near my office, I've measured daytime illumination. At the least obstructed spot, midday it was 40K lux in the sunny summer, but late fall 9K was as good as it got when moderately cloudy. In late fall it's identifiably daylight (if barely) at 9:00 and getting dark by 15:00 even though sunrise/sunset times promise 8.75 daytime hours in early December. A couple of notable consequences are a high rate of seasonal depression, and widespread vitamin D insufficiency. Light is a cue for circadian rhythm, and people sensitive to fall/winter darkness often benefit with phototherapy. I'd make sure to take vitamin D supplements too, usually 2K IU is a standard recommendation.