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Cambridge Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cambridge Bay clear sky chart from 2005-11-05 to 2017-02-18.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
51%
13252
4%
46209
4%
13240
51%
13240
11%
36156

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
61%
984
6%
4278
8%
984
62%
984
11%
3161
January16th to endNight
62%
1009
9%
3781
10%
1009
64%
1009
15%
2659
February1st to 15thNight
64%
894
10%
2959
9%
890
66%
890
18%
2096
February16th to endNight
60%
735
7%
2139
4%
735
61%
735
18%
1590
March1st to 15thNight
65%
685
8%
2083
7%
685
66%
685
15%
1573
March16th to endNight
61%
590
5%
1847
4%
590
62%
590
17%
1369
April1st to 15thNight
61%
494
0%
1375
0%
494
61%
494
23%
971
April16th to endNight
59%
338
0%
1014
0%
338
59%
338
13%
781
May1st to 15thNight
47%
165
0%
576
0%
165
47%
165
14%
426
May16th to endNight
42%
49
0%
91
0%
49
42%
49
15%
82
June1st to 15thNight00000
June16th to endNight00000
July1st to 15thNight00000
July16th to endNight
53%
80
0%
168
0%
73
54%
73
20%
137
August1st to 15thNight
54%
212
0%
709
0%
211
54%
211
16%
508
August16th to endNight
46%
408
0%
1179
0%
408
46%
408
14%
942
September1st to 15thNight
38%
495
0%
1466
0%
495
38%
495
9%
1230
September16th to endNight
28%
550
1%
1801
1%
550
28%
550
6%
1564
October1st to 15thNight
20%
770
1%
2141
1%
770
20%
770
4%
1972
October16th to endNight
26%
880
2%
2687
1%
880
27%
880
4%
2436
November1st to 15thNight
42%
899
3%
3127
2%
899
43%
899
7%
2636
November16th to endNight
47%
969
3%
3860
4%
969
48%
969
6%
3197
December1st to 15thNight
53%
990
3%
4320
5%
990
54%
990
8%
3397
December16th to endNight
61%
1056
5%
4608
7%
1056
62%
1056
10%
3429

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
11%10%5%9%8%46%6%6%7%22%
46594
Night
6%9%5%10%10%6%9%9%8%9%14%
46214
TransparencyDay
58%8%15%14%2
46079
Night
59%10%14%13%2
46211
SeeingDay
14%112%25%30%15%
7813
Night
10%111%27%32%17%
13262

By Month

Percentage Cloud Cover NW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January16th to endDay
25%36%9%6%8%12%9%15%21%
441
February1st to 15thDay
2337%8%7%9%12%11%15%18%
905
16th to endDay
2439%10%6%10%12%7%11%21%
1093
March1st to 15thDay
2436%12%7%11%11%9%14%14%
1558
16th to endDay
46%5%9%10%6%10%11%10%10%14%
2020
April1st to 15thDay
6%8%46%8%5%10%11%9%8%19%
2242
16th to endDay
5%9%5%12%12%9%11%6%5%7%12%
2615
May1st to 15thDay
6%11%6%11%12%6%8%5%6%7%19%
3045
16th to endDay
5%10%9%15%9%45%5%5%7%20%
3852
June1st to 15thDay
13%15%7%8%5%35%45%6%23%
3960
16th to endDay
13%13%46%6%2445%8%31%
3960
July1st to 15thDay
10%7%36%6%45%45%7%37%
3960
16th to endDay
19%7%46%6%35%45%8%28%
3774
August1st to 15thDay
11%7%36%435%5%5%9%36%
2916
16th to endDay
18%11%47%6%25%46%7%23%
2668
September1st to 15thDay
17%14%7%8%5%3445%5%21%
2164
16th to endDay
18%19%9%12%6%2234416%
1829
October1st to 15thDay
18%19%10%16%10%442227%
1477
16th to endDay
16%17%6%13%14%7%5%5%228%
1185
November1st to 15thDay
6%14%9%12%11%6%11%8%5%49%
731
16th to endDay
18%7%14%11%10%5%9%18%6%7%
199
January1st to 15thNight
36%38%10%6%12%10%10%13%12%
4278
16th to endNight
15%38%9%7%11%12%10%11%17%
3781
February1st to 15thNight
1437%10%7%10%11%12%15%14%
2947
16th to endNight
146%10%10%6%9%11%9%12%17%
2139
March1st to 15thNight
36%46%9%7%14%11%10%10%15%
2083
16th to endNight
26%49%10%5%10%10%9%12%17%
1846
April1st to 15thNight
7%5%37%8%5%8%9%9%7%27%
1375
16th to endNight
5%7%310%9%7%11%8%5%7%22%
1014
May1st to 15thNight
5%10%6%11%11%47%425%30%
576
16th to endNight
7%5%7%18%16%326%6%420%
91
July16th to endNight
18%12%17%7%6%4346%27%
183
August1st to 15thNight
12%6%38%6%35%8%6%6%32%
712
16th to endNight
21%12%37%6%23448%24%
1179
September1st to 15thNight
13%17%9%9%6%25%5%5%6%19%
1466
16th to endNight
18%19%8%15%5%2223316%
1801
October1st to 15thNight
18%20%9%13%12%442229%
2141
16th to endNight
18%17%6%15%11%6%432310%
2687
November1st to 15thNight
7%14%6%13%11%6%9%8%6%6%10%
3127
16th to endNight
28%6%13%12%7%11%10%8%7%10%
3860
December1st to 15thNight
37%5%10%13%8%10%9%8%11%11%
4320
16th to endNight
35%39%10%6%11%13%12%10%12%
4608

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January16th to endDay
43%8%17%23%7%
441
February1st to 15thDay
44%9%15%27%3
905
16th to endDay
49%10%14%18%7%
1093
March1st to 15thDay
53%8%17%16%4
1558
16th to endDay
56%9%11%15%6%
2021
April1st to 15thDay
54%9%14%14%6%
2242
16th to endDay
68%9%7%13%1
2615
May1st to 15thDay
63%7%9%14%4
3045
16th to endDay
63%8%11%15%
3857
June1st to 15thDay
61%7%15%14%1
3960
16th to endDay
51%9%21%15%1
3960
July1st to 15thDay
46%8%16%24%3
3711
16th to endDay
54%9%22%12%
3524
August1st to 15thDay
44%9%24%19%1
2894
16th to endDay
58%11%20%9%
2668
September1st to 15thDay
63%9%18%7%
2164
16th to endDay
72%7%12%6%
1829
October1st to 15thDay
83%5%6%4
1477
16th to endDay
79%8%7%4
1185
November1st to 15thDay
72%9%8%7%1
731
16th to endDay
60%15%8%14%2
199
January1st to 15thNight
54%11%17%15%1
4278
16th to endNight
49%10%15%19%5%
3781
February1st to 15thNight
47%10%16%22%2
2959
16th to endNight
50%9%15%19%5%
2139
March1st to 15thNight
52%10%15%16%4
2083
16th to endNight
52%9%12%19%5%
1849
April1st to 15thNight
46%7%17%22%6%
1375
16th to endNight
56%10%9%19%4
1014
May1st to 15thNight
58%5%12%17%6%
576
16th to endNight
65%9%10%9%3
91
July16th to endNight
57%7%17%17%
168
August1st to 15thNight
49%10%22%15%2
709
16th to endNight
60%8%21%9%
1179
September1st to 15thNight
64%11%16%7%
1466
16th to endNight
74%7%11%6%
1801
October1st to 15thNight
81%6%7%4
2141
16th to endNight
79%6%7%5%
2687
November1st to 15thNight
68%9%12%7%1
3127
16th to endNight
64%12%11%10%
3860
December1st to 15thNight
60%11%16%10%
4320
16th to endNight
52%13%20%12%
4608

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January16th to endDay
48%44%32%12%
25
February1st to 15thDay
37%9%44%35%
54
16th to endDay
5%230%53%7%
39
March1st to 15thDay
217%53%26%
45
16th to endDay
4111%27%33%22%
196
April1st to 15thDay
7%111%26%34%18%
339
16th to endDay
7%112%27%29%21%
375
May1st to 15thDay
11%12%26%31%16%
606
16th to endDay
7%19%26%36%18%
872
June1st to 15thDay
17%216%26%25%12%
915
16th to endDay
18%211%27%27%12%
915
July1st to 15thDay
13%110%24%33%16%
865
16th to endDay
22%112%24%28%9%
832
August1st to 15thDay
14%110%23%33%16%
560
16th to endDay
21%111%20%29%14%
443
September1st to 15thDay
21%314%25%22%13%
351
16th to endDay
24%115%21%26%10%
162
October1st to 15thDay
5%316%25%36%12%
90
16th to endDay
10%217%31%29%8%
82
November1st to 15thDay
3313%20%26%33%
30
16th to endDay
11%17%11%47%11%
17
January1st to 15thNight
4110%29%35%18%
989
16th to endNight
313%32%35%15%
1009
February1st to 15thNight
312%26%35%22%
898
16th to endNight
210%28%38%19%
735
March1st to 15thNight
419%23%40%21%
685
16th to endNight
319%27%39%19%
591
April1st to 15thNight
8%11%30%35%13%
494
16th to endNight
7%19%26%34%21%
338
May1st to 15thNight
10%13%29%29%17%
165
16th to endNight
12%2430%40%10%
49
July16th to endNight
18%5%8%31%30%6%
80
August1st to 15thNight
14%11%25%35%11%
212
16th to endNight
27%111%24%27%7%
408
September1st to 15thNight
20%313%27%25%9%
495
16th to endNight
27%211%25%23%10%
550
October1st to 15thNight
29%213%24%21%7%
770
16th to endNight
24%312%25%24%10%
880
November1st to 15thNight
12%113%24%32%15%
899
16th to endNight
5%112%28%27%23%
969
December1st to 15thNight
4113%28%33%17%
990
16th to endNight
5%9%24%33%26%
1056
Page generated at 2017-02-18 14:04:32. Version ac04

Copyright 2017 A. Danko


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