Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
The sunshine mean might be reduced a little by nearby hills if the station is close to them. But it's a horrendous climate, even if the open-horizon value were 100-200 hours more.
Back in the day when some NWS Offices had sunshine measuring machines.... I was an intern at WSO Detroit Michigan (Metro Airport) in the early 90s and the sunshine recorder would record sun as long as there was a shadow -- i.e. you could have an overcast of thin cirrus but enough sunlight through to turn on the machine and you could get 100 pct sunshine if the entire day stayed thin cirrus. On days with mix of cloud/sun it would turn on of course when sun is out but turn off when no shadow was observed.
Note that there are no longer sunshine measuring units at NWS offices in the U.S. I think there is a cooperative observer at Chicago that has one but that is about it for measuring sunshine hours in the states. Hence when you look at NOAA sunshine average hours most have the latest 30 yr data period as 1961-1990.
Yes, this sunshine data is 100% correct. The place is, indeed, one of the gloomiest of the world, if not the most. As RWood pointed out, nearby hills can reduce the real/ideal number. It had already been discussed here, so I managed to contact with the people from the station. Effectively, there are surrounding elevations that in months can block the sunlight when it is very low over the horizon, but apparently the percentage of lost hours is low. Let's say this must be a very common problem in this kind of high latitude oceanic islands.
As for the pattern of the sunshine throughout the year, the island is perpetually affected by the southern circumpolar lows, which provide the almost everlasting cloud cover. It's only broken when Antarctic fronts beat the island in the winter (look at the extreme low temps), whereas the time of highest sunshine roughly coincides with the time of the year in which the ice sea reaches its maximum extension, favouring slightly cleaner skies.
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
