Quote:
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.
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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