This page made possible by the sponsorship of: RASC Ottawa Centre, Jimmy Book.

Carp Library / Diefenbunker
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carp Library / Diefenbunker clear sky chart from 2005-11-05 to 2017-09-10.

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
31%
14627
14%
46788
9%
14596
38%
14596
18%
32656

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
16%
720
7%
2506
4%
716
22%
716
8%
1999
January16th to endNight
22%
768
12%
2633
7%
768
29%
768
12%
1928
February1st to 15thNight
19%
703
11%
2287
5%
701
26%
701
12%
1714
February16th to endNight
24%
631
14%
1955
6%
631
34%
631
14%
1431
March1st to 15thNight
22%
720
13%
2091
7%
720
29%
720
16%
1551
March16th to endNight
31%
768
20%
2040
10%
768
39%
768
23%
1377
April1st to 15thNight
23%
718
16%
1796
6%
718
28%
718
20%
1304
April16th to endNight
31%
644
18%
1724
9%
644
37%
644
23%
1192
May1st to 15thNight
35%
360
17%
1440
17%
360
44%
360
18%
924
May16th to endNight
36%
375
14%
1497
11%
374
49%
374
20%
939
June1st to 15thNight
38%
360
10%
1440
9%
360
47%
360
17%
929
June16th to endNight
45%
360
9%
1440
12%
360
51%
360
20%
882
July1st to 15thNight
54%
340
15%
1360
21%
340
60%
340
29%
727
July16th to endNight
56%
376
15%
1418
18%
354
60%
354
28%
775
August1st to 15thNight
55%
452
16%
1523
14%
450
60%
450
28%
905
August16th to endNight
52%
703
21%
1849
11%
703
57%
703
38%
1128
September1st to 15thNight
46%
700
16%
1750
8%
700
48%
700
30%
1187
September16th to endNight
48%
657
22%
1798
14%
657
53%
657
32%
1143
October1st to 15thNight
35%
660
19%
1980
12%
660
44%
660
21%
1356
October16th to endNight
26%
704
12%
2194
6%
704
34%
704
14%
1640
November1st to 15thNight
29%
700
17%
2339
13%
700
37%
700
17%
1615
November16th to endNight
20%
720
11%
2520
7%
720
27%
720
10%
1904
December1st to 15thNight
19%
720
8%
2520
4%
720
24%
720
9%
1974
December16th to endNight
15%
768
10%
2688
4%
768
22%
768
9%
2132

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
17%8%36%5%35%45%6%33%
47848
Night
17%9%46%5%34446%32%
46957
Cloud CoverDay
21%7%35%5%34446%33%
47857
Night
20%8%36%5%24445%33%
46963
TransparencyDay
50%312%21%10%1
47535
Night
52%311%21%10%
46788
SeeingDay
21%10%28%23%12%4
5438
Night
23%9%27%28%10%
14628

By Month

Percentage Cloud Cover NE (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
January1st to 15thDay
21%13%49%8%35%345%21%
1432
16th to endDay
14%15%48%7%45%35%6%23%
1590
February1st to 15thDay
13%13%5%11%7%45%45%423%
1575
16th to endDay
17%13%48%7%25%445%27%
1517
March1st to 15thDay
17%10%46%8%36%5%4428%
1856
16th to endDay
15%8%35%424446%40%
2184
April1st to 15thDay
23%8%36%423345%34%
2152
16th to endDay
20%8%25%5%23445%37%
2244
May1st to 15thDay
19%7%36%5%35%346%33%
2511
16th to endDay
17%5%35%6%35%45%6%35%
2618
June1st to 15thDay
20%6%35%5%36%45%8%30%
2520
16th to endDay
16%6%35%5%35%6%6%7%32%
2520
July1st to 15thDay
12%5%245%36%6%6%8%39%
2520
16th to endDay
11%5%25%436%5%7%9%38%
2654
August1st to 15thDay
10%5%26%5%36%6%6%8%38%
2425
16th to endDay
10%5%25%435%5%6%8%41%
2339
September1st to 15thDay
16%5%25%5%25%5%47%40%
2098
16th to endDay
14%5%2442345%7%43%
1831
October1st to 15thDay
20%7%36%43445%6%33%
1650
16th to endDay
26%8%46%6%34436%25%
1678
November1st to 15thDay
15%8%35%5%45%5%5%6%33%
1518
16th to endDay
22%11%5%7%6%25%445%24%
1440
December1st to 15thDay
20%15%48%8%45%5%46%16%
1440
16th to endDay
23%14%6%8%7%1433421%
1536
January1st to 15thNight
18%14%6%11%8%34435%18%
2506
16th to endNight
12%16%6%8%6%35%345%27%
2633
February1st to 15thNight
13%13%5%11%8%35%445%23%
2285
16th to endNight
17%10%48%7%3435%5%28%
1955
March1st to 15thNight
18%11%5%8%6%34335%30%
2078
16th to endNight
15%6%45%5%25%34442%
2040
April1st to 15thNight
22%8%35%5%24345%35%
1796
16th to endNight
17%8%26%5%33346%37%
1724
May1st to 15thNight
21%7%25%42345%6%35%
1440
16th to endNight
15%6%25%5%335%5%7%37%
1495
June1st to 15thNight
17%6%26%6%245%5%7%34%
1440
16th to endNight
16%6%24425%5%6%8%37%
1440
July1st to 15thNight
10%314435%5%5%9%46%
1440
16th to endNight
9%5%235%35%5%6%9%45%
1514
August1st to 15thNight
9%5%35%4345%6%9%42%
1533
16th to endNight
9%324425%45%7%49%
1849
September1st to 15thNight
15%5%25%5%2445%5%42%
1750
16th to endNight
16%415%323335%49%
1798
October1st to 15thNight
19%7%35%5%25%45%6%35%
1980
16th to endNight
25%9%36%5%34446%26%
2194
November1st to 15thNight
19%9%36%5%33445%32%
2339
16th to endNight
23%10%48%6%34445%24%
2520
December1st to 15thNight
22%15%48%5%35%5%45%19%
2520
16th to endNight
24%15%5%8%6%2433419%
2688

Percentage Cloud Cover SE (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
January1st to 15thDay
21%13%5%8%8%35%345%21%
1432
16th to endDay
14%15%48%8%35%445%24%
1590
February1st to 15thDay
14%13%411%8%35%45%424%
1575
16th to endDay
18%13%47%6%25%43427%
1517
March1st to 15thDay
26%8%346%2443331%
1866
16th to endDay
24%6%2432333439%
2183
April1st to 15thDay
26%8%35%423335%33%
2152
16th to endDay
24%6%24423435%36%
2244
May1st to 15thDay
28%6%35%5%2424431%
2511
16th to endDay
27%4245%34345%34%
2618
June1st to 15thDay
25%5%345%35%446%31%
2520
16th to endDay
21%5%25%5%35%5%6%6%33%
2520
July1st to 15thDay
12%5%145%35%6%6%8%39%
2520
16th to endDay
11%5%25%435%5%7%9%38%
2654
August1st to 15thDay
22%314435%5%5%6%37%
2425
16th to endDay
21%41432445%7%40%
2339
September1st to 15thDay
16%5%25%5%24447%40%
2098
16th to endDay
15%5%2343345%7%43%
1831
October1st to 15thDay
20%7%36%43445%6%34%
1650
16th to endDay
25%8%46%6%34445%26%
1678
November1st to 15thDay
19%7%35%435%45%6%33%
1518
16th to endDay
24%11%47%5%34435%25%
1440
December1st to 15thDay
21%15%48%7%45%5%45%17%
1440
16th to endDay
23%14%5%7%7%24235%22%
1536
January1st to 15thNight
18%14%6%11%7%3444419%
2506
16th to endNight
13%16%6%8%6%24345%27%
2633
February1st to 15thNight
14%12%5%11%7%35%445%25%
2278
16th to endNight
18%10%48%7%3435%5%29%
1955
March1st to 15thNight
28%8%36%42322432%
2091
16th to endNight
25%5%3431433342%
2040
April1st to 15thNight
25%7%35%423245%35%
1796
16th to endNight
20%7%25%5%33346%37%
1724
May1st to 15thNight
26%6%24423345%34%
1440
16th to endNight
21%5%345%23447%37%
1495
June1st to 15thNight
19%5%25%5%3445%6%35%
1440
16th to endNight
18%5%24425%5%5%7%37%
1440
July1st to 15thNight
10%323435%5%5%9%46%
1440
16th to endNight
8%5%235%35%46%9%45%
1514
August1st to 15thNight
14%425%323447%45%
1533
16th to endNight
16%314314345%50%
1849
September1st to 15thNight
15%5%25%5%345%5%5%42%
1750
16th to endNight
16%5%15%323335%49%
1798
October1st to 15thNight
19%7%34425%35%6%36%
1980
16th to endNight
25%8%36%5%44436%26%
2194
November1st to 15thNight
24%8%35%42334434%
2339
16th to endNight
27%9%38%423345%27%
2520
December1st to 15thNight
23%14%37%5%3445%5%20%
2520
16th to endNight
25%14%5%8%6%2433421%
2688

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
January1st to 15thDay
65%29%14%6%
1433
16th to endDay
61%211%14%8%
1590
February1st to 15thDay
62%311%17%4
1577
16th to endDay
58%310%16%9%1
1517
March1st to 15thDay
58%311%17%7%1
1866
16th to endDay
45%29%20%16%6%
2184
April1st to 15thDay
53%17%20%14%2
2152
16th to endDay
49%26%20%17%3
2244
May1st to 15thDay
51%27%21%14%2
2511
16th to endDay
47%411%21%12%2
2622
June1st to 15thDay
51%410%22%9%
2520
16th to endDay
47%313%22%11%1
2520
July1st to 15thDay
38%414%29%12%
2371
16th to endDay
40%5%16%27%10%
2487
August1st to 15thDay
41%418%23%11%
2411
16th to endDay
38%415%30%11%
2339
September1st to 15thDay
42%413%28%11%
2098
16th to endDay
39%413%33%9%
1831
October1st to 15thDay
50%313%22%9%
1650
16th to endDay
61%312%15%6%
1678
November1st to 15thDay
49%414%22%8%
1518
16th to endDay
62%312%13%6%1
1440
December1st to 15thDay
68%411%13%2
1440
16th to endDay
66%311%12%5%
1536
January1st to 15thNight
67%49%12%5%
2506
16th to endNight
59%39%18%8%
2633
February1st to 15thNight
61%311%17%5%
2287
16th to endNight
57%210%19%9%
1955
March1st to 15thNight
57%29%20%8%
2091
16th to endNight
46%29%20%16%4
2040
April1st to 15thNight
52%27%20%16%1
1796
16th to endNight
48%26%20%17%3
1724
May1st to 15thNight
49%27%20%15%4
1440
16th to endNight
45%411%22%14%2
1497
June1st to 15thNight
47%412%23%10%1
1440
16th to endNight
43%5%12%22%15%
1440
July1st to 15thNight
32%5%12%32%15%1
1360
16th to endNight
34%415%29%15%
1418
August1st to 15thNight
37%418%25%12%1
1523
16th to endNight
33%315%34%12%
1849
September1st to 15thNight
42%411%29%10%
1750
16th to endNight
38%311%35%10%
1798
October1st to 15thNight
48%310%24%12%
1980
16th to endNight
58%412%17%6%
2194
November1st to 15thNight
52%313%19%10%
2339
16th to endNight
61%411%17%5%
2520
December1st to 15thNight
65%312%14%3
2520
16th to endNight
68%29%13%5%
2688

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
January1st to 15thDay
28%26%21%20%11
60
16th to endDay
27%17%31%19%4
73
February1st to 15thDay
28%24%28%17%
90
16th to endDay
33%18%25%15%6%
176
March1st to 15thDay
25%13%30%26%4
270
16th to endDay
23%15%29%19%9%2
288
April1st to 15thDay
27%18%27%18%6%1
270
16th to endDay
25%13%27%17%12%3
270
May1st to 15thDay
28%9%30%18%8%4
288
16th to endDay
20%11%32%22%11%1
331
June1st to 15thDay
24%7%31%23%10%2
315
16th to endDay
16%8%32%26%13%2
315
July1st to 15thDay
14%428%30%14%6%
305
16th to endDay
13%328%26%21%6%
326
August1st to 15thDay
12%322%35%17%8%
313
16th to endDay
13%325%26%18%12%
332
September1st to 15thDay
20%6%20%17%23%11%
294
16th to endDay
17%5%27%23%16%9%
254
October1st to 15thDay
21%9%25%23%17%2
255
16th to endDay
31%13%24%21%8%
257
November1st to 15thDay
19%11%28%26%12%1
172
16th to endDay
33%13%31%15%6%
60
December1st to 15thDay
26%11%40%18%3
60
16th to endDay
37%18%37%41
64
January1st to 15thNight
25%14%32%21%5%
720
16th to endNight
22%12%30%27%6%
768
February1st to 15thNight
20%13%36%23%5%
704
16th to endNight
24%14%29%25%5%
631
March1st to 15thNight
25%12%31%27%3
720
16th to endNight
20%14%25%28%10%
768
April1st to 15thNight
27%12%28%24%5%
718
16th to endNight
23%11%28%27%8%
644
May1st to 15thNight
25%6%25%30%10%1
360
16th to endNight
18%5%33%28%13%
375
June1st to 15thNight
19%5%27%34%13%
360
16th to endNight
18%323%39%13%1
360
July1st to 15thNight
10%125%43%17%1
340
16th to endNight
10%321%45%17%2
376
August1st to 15thNight
13%218%40%23%1
452
16th to endNight
10%420%38%23%2
703
September1st to 15thNight
18%424%30%20%2
700
16th to endNight
18%5%23%28%20%2
657
October1st to 15thNight
24%8%23%28%12%1
660
16th to endNight
30%10%24%26%7%
704
November1st to 15thNight
25%8%27%24%12%
700
16th to endNight
30%13%25%20%9%
720
December1st to 15thNight
30%13%29%22%4
720
16th to endNight
33%11%28%19%41
768
Page generated at 2017-09-11 19:35:31. Version ac04

Copyright 2017 A. Danko


Carp Library / Diefenbunker Clear Sky Chart | Charts Home