Sunny days per annum

[wembley]

I've noticed that apart from Wikipedia stating that Wellington had 169 sunny days per annum, statistics for sunny and partly sunny days per year are not included in a centre's weather stats. By sunny days I mean days with 0-2 oktas of cloud cover observed at 9am and 3pm and partly sunny days are days with 2-6 oktas of cloud observed at those two times. Overcast days are days with more than 6 oktas BTW.

[NZstorm]

'Sunny days' is not a climate parameter I have ever come across before.

[wembley]

Here is a link which shows this climate parameter

http://www.currentresults.com/Weather/A ... verage.php

[NZstorm]

Whether Met Service/ NIWA have ever assembled such data I don't know.

Some of those aussie sunshine hours look good. 3200hrs for Perth!

[RWood]

Such counts are not very precise and are not used in NZ in published climate assessments by MetService/NIWA and their predecessor(s). Bright sunshine hours are used (though since the introduction of EWS measurements these are problematical in that there are two different kinds of measuring going on, and the differences raise quite a number of questions). In the US, where sunshine measurement has virtually disappeared with the exception of a handful of sites, those rough categories are quoted.

Perth's numbers have tended upwards in conjunction with the drying out in the SW of Australia over recent decades.

A small portion of Australia experiences over 3500 hours per annum.

[Michael]

Be interesting to know a 24hr clear period,but then at night it have to be measured guess on % of clear sky to count as the sun isn't measured.

[igaquo1]

I've never quite worked out why Rotorua is so sunny, compared to Taupo not far down the road, and it always seems to be misty or foggy there up in the hills when I'm there.

[Willoughby]

Rotorua is immediately sheltered to the W/SW being at the bottom of the caldera, lake to the NE. Taupo is rather exposed to the W/SW, large caldera lake to the SW.

[RWood]

Rotorua is immediately sheltered to the W/SW being at the bottom of the caldera, lake to the NE. Taupo is rather exposed to the W/SW, large caldera lake to the SW.

In the days when both were recording sunshine (neither is now), Rotorua's advantage was only about +10% or +200 hours, not a huge difference though noticeable.

[igaquo1]

I wouldn't turn down another 200 hrs. Only 1550hrs a year here in London.

So what have they replaced measuring sunshine hours with?

[RWood]

I wouldn't turn down another 200 hrs. Only 1550hrs a year here in London.

So what have they replaced measuring sunshine hours with?

Nothing for those 2 places, along with quite a few others with former manual equipment - eg Wanganui. However EWS instruments are being installed by slow degrees across the country and probably both will have them eventually. The Taupo figures when being recorded may have been lowered a little by site limitations. Back in January 1950 Taupo had the highest equal total ever recorded in NZ - 335 hours.

BTW, the 1981-2010 averages show Kew with 1653 and I think Heathrow is around the 1600 mark from memory.

[igaquo1]

I wouldn't turn down another 200 hrs. Only 1550hrs a year here in London.

So what have they replaced measuring sunshine hours with?

Nothing for those 2 places, along with quite a few others with former manual equipment - eg Wanganui. However EWS instruments are being installed by slow degrees across the country and probably both will have them eventually. The Taupo figures when being recorded may have been lowered a little by site limitations. Back in January 1950 Taupo had the highest equal total ever recorded in NZ - 335 hours.

BTW, the 1981-2010 averages show Kew with 1653 and I think Heathrow is around the 1600 mark from memory.

Greenwich, which is closer to central London than Kew or Heathrow has a 1981 -2010 average of 1410 hrs. Where I am is about 1550 hrs based on the climate maps.

[RWood]

I wouldn't turn down another 200 hrs. Only 1550hrs a year here in London.

So what have they replaced measuring sunshine hours with?

Nothing for those 2 places, along with quite a few others with former manual equipment - eg Wanganui. However EWS instruments are being installed by slow degrees across the country and probably both will have them eventually. The Taupo figures when being recorded may have been lowered a little by site limitations. Back in January 1950 Taupo had the highest equal total ever recorded in NZ - 335 hours.

BTW, the 1981-2010 averages show Kew with 1653 and I think Heathrow is around the 1600 mark from memory.[/quote]

Greenwich, which is closer to central London than Kew or Heathrow has a 1981 -2010 average of 1410 hrs. Where I am is about 1550 hrs based on the climate maps.[/quote]

I've seen comment on other forums that the Greenwich figure is artificially low due to horizon obstruction. Can't remember the conclusions if any were safely drawn ...