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Possibly, but why the differences within London at Heathrow vs. Greenwich? Between Detroit and Windsor we are talking 170 hours spread over an entire year. 27 minutes a day. Look at the blown up map from Canada's weather service. Leaving Toronto you lose 200 hours very quickly heading northwest. I seriously don't think this in and of itself is enough to start lopping off 300 sun hours from US cities to compare to the rest of the world.
Could be the same phenomenon at various sites... London is a very built up area with relatively flat topography... perhaps the Greenwich sunshine recorder is blocked from getting more sun by surrounding structures than Heathrow... Heathrow is an airport and is likely to be more open to allow planes to land.
I'm not saying that we need to lop off 300 hours of sun from US locations, merely that there are many variables one has to take into consideration.
It's a bit approximate - I prefer tables. Also, quite a number of sites have had a significant increase with the pending update to 1981-2010. Some parts of the chart are using very sparse information, and in the case of the 900-1400 zone shown on the West Coast, that is completely misleading. A single site there was very close to the mountain chain and subject to a lot of daylight loss, averaging about 1175 hours. A new site nearer the village is now giving an average about 400 hours higher than this.
Could be the same phenomenon at various sites... London is a very built up area with relatively flat topography... perhaps the Greenwich sunshine recorder is blocked from getting more sun by surrounding structures than Heathrow... Heathrow is an airport and is likely to be more open to allow planes to land.
I'm not saying that we need to lop off 300 hours of sun from US locations, merely that there are many variables one has to take into consideration.
Even though it is an observatory, I too suspect that Greenwich has less recordable sunlight than Heathrow has, so that might inflate the difference a little artificially. For 1971-2000 Heathrow was about 1575 and Greenwich about a 100 hours lower (not quite certain about Greenwich).
No, no…you missed it lad…the question was related to annual number of sun hrs at Pitt and Baltimore; From what I remember, Pitt averages something like 1900/2000 hrs of sunshine annually (due to its proximity to the Great Lakes)….while Baltimore averages around 2500/2600 hrs of sun annually(2550 – 1900 = 25 % or so difference)….the same with the winter differences (look at the map of Feb a few pages ago) Pitt gets like 115 hrs of sun in Jan/Feb….while Baltimore gets like 165 hrs of sun in Feb. Most people would not think the sun hrs is so large in such a short distance between Pitt and Balt/DC.
As far as Cleveland getting more annual % than Pitt…I was unaware of that. The only thing I can think of is that that the Allegheny Mts in western PA tend to have a lot of fog – perhaps this impacts total annual %?
I'm not sure if they account for fog and it appears Pittsburgh is not directly in the Alleghenies like Altoona but a bit west (Allegheny Plateau). I've always wondered about the steel industry and smoke covered skies that used to occur there. From what I heard, back in those days, Pittsburgh used to look like a perpetual twilight. I've only visited Pitt and it's been sunny each time I went. I was surprised at it's sunshine stats, because I used to think the further south or west you go, the sunnier it gets. I'm starting to understand the effects of mountains, plateaus, and the Great Lakes. Not surprisingly, the geography between my hometown of Scranton is similar to Pittsburgh, and sunshine hours not that far off.
Going back to the difference in sunshine hours, what is the difference between total sunshine hours and annual percentage of possible sunshine? I thought they were related.
The best thing to do is obtain the actual daily hours from BOM yourself, there's a little fee involved of course which is quite cheaper in the pound and euro currencies, but it's worth it as obtaining "monthly' statistics doesn't really paint a accurate picture. I simply sum up the dailies for a particular month and the actual monthly total is given. I've discovered that by using the monthly totals, without the dailies, the total can be somewhat misleading and the margin of error can be as much as one hour
I'm not sure if they account for fog and it appears Pittsburgh is not directly in the Alleghenies like Altoona but a bit west (Allegheny Plateau). I've always wondered about the steel industry and smoke covered skies that used to occur there. From what I heard, back in those days, Pittsburgh used to look like a perpetual twilight. I've only visited Pitt and it's been sunny each time I went. I was surprised at it's sunshine stats, because I used to think the further south or west you go, the sunnier it gets. I'm starting to understand the effects of mountains, plateaus, and the Great Lakes. Not surprisingly, the geography between my hometown of Scranton is similar to Pittsburgh, and sunshine hours not that far off.
Going back to the difference in sunshine hours, what is the difference between total sunshine hours and annual percentage of possible sunshine? I thought they were related.
Yes, of course they are related, but you have to check whether the information service is using astronomical daylight length as the maximum possible, or if this has been reduced because of obstructions or limitations in measuring equipment.
The best thing to do is obtain the actual daily hours from BOM yourself, there's a little fee involved of course which is quite cheaper in the pound and euro currencies, but it's worth it as obtaining "monthly' statistics doesn't really paint a accurate picture. I simply sum up the dailies for a particular month and the actual monthly total is given. I've discovered that by using the monthly totals, without the dailies, the total can be somewhat misleading and the margin of error can be as much as one hour
You are dead right on this one.
A few years ago I obtained about 20 years of records for all NSW centres for about $30 in total.
Generally government services such as this are not for profit.
Unfortunately my old computer crashed and I never backed up the records. (Should have stored it on a CD or Memory Stick!).
Location: The western periphery of Terra Australis
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Quote:
Originally Posted by deneb78
Wow... 2550 hours of sun AND a record low of only -5.2°C at 41°S... no wonder they call Australia the lucky country
Hobart's record low is only -2.8C. Some locations in NZ like Kaikoura have record lows of like -1C. Maatsuyker Island is like -0.6C and that's right at the bottom of Tasmania. Extremely maritime climates.
The record low for Albany Town on the coast is a pretty absurd 2.1C (it's 35'S): Broome, like 2500 km to the north, has reported 3.2C and if stats are to believed Kalumburu even further north near the coast has got down to 0.6C but I'm skeptical. That's like somewhere like Ottawa having the same record low as Miami.
I always find these maps very interesting for getting a national overview.
What always struck me was the sunniest part of Oz - that part with over an average of 10 hours a day (3650 a year) is centered around the West Coast from Port Hedland to Coral Bay. Mardie has gone over a year without rain, so I've heard, and a significant portion of the rain of the area is actually from unpredictable tropical cyclones. The sunniest part isn't, as some might expect, deep in the inland heart.
Also one thing which has always struck me as weird was how Perth is sunnier than Kalgoorlie, right on edge of the desert! Cloudiness in Perth is actually sort of fleeting even in winter. It's rare to go more than 48 hours without seeing the sun. North of about 34'S cloud doesn't seem to linger very much.
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