I have 2 questions (records, temperatures, 2014, days)

[Maxwell Senf]

I have two completely unrelated questions.

I know that US sunshine hours are overrepresented compared to the rest of the world. Although there isn't one definitive answer to this question, by about how much are the U.S. sunshine hours overrepresented? Is it about 200-300 hours? That's about the difference between Detroit/Windsor and Seattle/Vancouver. Side note: I wonder if the temperatures are also reported on the high side. I know there's an urban heat island effect in Detroit, so maybe that explains the temperature differences.

Where can I find historical data on cloud coverage percentage? On weatherunderground, it shows the cloudiness percentage on the forecast, but I can't find historical data on it. Is that available somewhere?

[nei]

There's several threads on that, maybe someone could do a search. US cloud coverage data is hard to find, might try digging in the NCDC.

[Glacierx]

Originally Posted by nei

There's several threads on that, maybe someone could do a search. US cloud coverage data is hard to find, might try digging in the NCDC.

USA cloud cover is easy to find, but it takes so work to compare nation to nation, not because the standards and methods are different, but because the method by which the data is written down is different.

Definition of terms:
Clear = 0 to 2 tenths cloud cover.
Partly Cloudy = 3 to 7 tenths cloud cover.
Cloudy = 8 to 10 tenths cloud cover.

The USA tends to use the left side while Canada tends to use the right side definition, but they are the same thing (I think). I suspect that the USA definition for "Clear" is not the same as 0 to 2 tenths. Instead, I looks like it may be more cloud-free than that.

Next, the USA data is listed in terms of days per month, while Canadian data is listed as hours per month. This is the exact same thing, except Canadian numbers are more precise. To convert one to the other multiply or divide by 24.

Let's start with Windsor and Detroit.

Windsor

MONTH..0 to 2 tenths..3 to 7 tenths..8 to 10 tenths
Jan…..…..132.6…..…..97.5…..…..513.9
Feb…..…..132.3…..…..98.3…..…..447.9
Mar…..…..186.3…..…..122…..…..435.7
Apr…..…..176.5…..…..129.3…..…..414.2
May…..…..207.4…..…..152.2…..…..384.4
Jun…..…..205…..…..196.7…..…..318.4
Jul…..…..224.1…..…..221.9…..…..298
Aug…..…..239.9…..…..201.9…..…..302.2
Sep…..…..247.8…..…..167.3…..…..304.9
Oct…..…..217.9…..…..139.1…..…..387
Nov…..…..135.9…..…..104.7…..…..479.4
Dec…..…..120…..…..90.8…..…..533.2
Year…..…..2225.8…..…..1721.6…..…..4819.3


Detroit
MONTH...Clr......PC......Cldy
Jan…..…..4…..…..7…..…..20
Feb…..…..5…..…..7…..…..17
Mar…..…..6…..…..7…..…..18
Apr…..…..6…..…..8…..…..16
May…..…..7…..…..10…..…..14
Jun…..…..8…..…..11…..…..11
Jul…..…..9…..…..12…..…..10
Aug…..…..9…..…..11…..…..11
Sep…..…..8…..…..10…..…..12
Oct…..…..8…..…..9…..…..15
Nov…..…..4…..…..7…..…..19
Dec…..…..3…..…..6…..…..22
Year…..…..75…..…..105…..…..185


To convert Windsor into Detroit we divide by 24.

MONTH..0 to 2 tenths..3 to 7 tenths..8 to 10 tenths
Jan…..…..5.5…..…..4.1…..…..21.4
Feb…..…..5.5…..…..4.1…..…..18.7
Mar…..…..7.8…..…..5.1…..…..18.2
Apr…..…..7.4…..…..5.4…..…..17.3
May…..…..8.6…..…..6.3…..…..16
Jun…..…..8.5…..…..8.2…..…..13.3
Jul…..…..9.3…..…..9.2…..…..12.4
Aug…..…..10…..…..8.4…..…..12.6
Sep…..…..10.3…..…..7…..…..12.7
Oct…..…..9.1…..…..5.8…..…..16.1
Nov…..…..5.7…..…..4.4…..…..20
Dec…..…..5…..…..3.8…..…..22.2
Year…..…..92.7…..…..71.7…..…..200.8


NEXT....

Seattle vs Victoria vs Vancouver (all in days per month)

SEATTLE:
MONTH...Clr......PC......Cldy
Jan…..…..3…..…..4…..…..24
Feb…..…..3…..…..4…..…..21
Mar…..…..3…..…..6…..…..22
Apr…..…..3…..…..7…..…..20
May…..…..4…..…..9…..…..18
Jun…..…..5…..…..8…..…..17
Jul…..…..10…..…..10…..…..11
Aug…..…..9…..…..10…..…..12
Sep…..…..8…..…..9…..…..13
Oct…..…..4…..…..7…..…..19
Nov…..…..2…..…..4…..…..23
Dec…..…..2…..…..4…..…..25
Year…..…..58…..…..82…..…..226

VICTORIA:
MONTH..0 to 2 tenths..3 to 7 tenths..8 to 10 tenths
Jan…..…..4…..…..4.5…..…..22.6
Feb…..…..5.3…..…..4.9…..…..18
Mar…..…..5.2…..…..6.3…..…..19.5
Apr…..…..5.6…..…..6.5…..…..17.9
May…..…..7.5…..…..7.1…..…..16.4
Jun…..…..7.2…..…..7.3…..…..15.5
Jul…..…..12.8…..…..7.4…..…..10.8
Aug…..…..13…..…..7.7…..…..10.3
Sep…..…..11.4…..…..7…..…..11.6
Oct…..…..6.9…..…..6…..…..18.2
Nov…..…..4.2…..…..4.7…..…..21.1
Dec…..…..3.9…..…..4.4…..…..22.7
Year…..…..87.1…..…..73.6…..…..204.5

VANCOUVER
MONTH..0 to 2 tenths..3 to 7 tenths..8 to 10 tenths
Jan…..…..3.9…..…..3.8…..…..23.3
Feb…..…..4.8…..…..4.5…..…..18.9
Mar…..…..5.2…..…..5.5…..…..20.4
Apr…..…..5.4…..…..6.3…..…..18.2
May…..…..6.5…..…..7.3…..…..17.3
Jun…..…..6…..…..7.2…..…..16.8
Jul…..…..11.4…..…..7.4…..…..12.2
Aug…..…..12…..…..7.7…..…..11.3
Sep…..…..10.5…..…..7.3…..…..12.2
Oct…..…..6.4…..…..5.7…..…..18.9
Nov…..…..3.9…..…..4.3…..…..21.8
Dec…..…..4.1…..…..4.2…..…..22.6
Year…..…..80.1…..…..71.2…..…..213.8

[Maxwell Senf]

Thank you that's quite helpful. The one thing I'm still struggling to find is individual daily records. I can find average clear/partly cloudy/cloudy days for most US cities but what I'd like to do is be able to look up a date in the past in a city, say, March 9, 2014 in Portland, and get cloud coverage info for that day. Temperature records are easy to access, but the cloudiness thing is trickier.

[nei]

Originally Posted by Glacierx

USA cloud cover is easy to find, but it takes so work to compare nation to nation, not because the standards and methods are different, but because the method by which the data is written down is different.

where'd you get it from? I've mostly found recent monthly observations not enough for an average.

[Maxwell Senf]

Currentresults.com. They use ncdc data. Where do you find the data you're referring to?

[Glacierx]

Originally Posted by Maxwell Senf

Currentresults.com. They use ncdc data. Where do you find the data you're referring to?

NCDC...http://www1.ncdc.noaa.gov/pub/data/c...a/clpcdy12.txt