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Kopernik Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kopernik Observatory clear sky chart from 2005-11-05 to 2019-09-17.

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
29%
17436
14%
54764
8%
17404
36%
17404
17%
38910

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%
840
9%
2926
5%
836
23%
836
9%
2256
January16th to endNight
13%
896
10%
2972
3%
896
22%
896
9%
2267
February1st to 15thNight
11%
824
9%
2677
2%
821
19%
821
9%
2097
February16th to endNight
15%
735
12%
2232
5%
735
23%
735
11%
1706
March1st to 15thNight
17%
840
13%
2420
6%
840
25%
840
13%
1848
March16th to endNight
20%
896
17%
2388
6%
896
29%
896
18%
1722
April1st to 15thNight
19%
838
14%
2096
4%
838
24%
838
18%
1580
April16th to endNight
26%
831
16%
2077
4%
831
32%
831
23%
1455
May1st to 15thNight
31%
487
17%
1747
10%
487
40%
487
16%
1212
May16th to endNight
37%
438
15%
1753
13%
438
47%
438
18%
1112
June1st to 15thNight
38%
420
16%
1680
15%
420
48%
420
17%
1080
June16th to endNight
50%
420
14%
1680
16%
420
57%
420
24%
970
July1st to 15thNight
59%
400
15%
1600
20%
400
63%
400
24%
942
July16th to endNight
57%
446
16%
1680
19%
424
61%
424
24%
980
August1st to 15thNight
57%
620
15%
1850
11%
617
60%
617
27%
1206
August16th to endNight
59%
875
18%
2213
10%
875
60%
875
33%
1462
September1st to 15thNight
46%
840
18%
2100
10%
840
49%
840
29%
1434
September16th to endNight
49%
782
24%
2130
18%
782
53%
782
32%
1375
October1st to 15thNight
36%
780
17%
2340
14%
780
43%
780
20%
1608
October16th to endNight
21%
832
14%
2541
7%
832
30%
832
16%
1841
November1st to 15thNight
24%
820
16%
2667
8%
820
34%
820
17%
1852
November16th to endNight
23%
840
14%
2919
8%
840
31%
840
13%
2087
December1st to 15thNight
18%
840
9%
2940
5%
840
23%
840
8%
2285
December16th to endNight
13%
896
6%
3136
2%
896
19%
896
7%
2533

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
16%9%47%6%35%45%6%30%
55933
Night
15%9%47%6%3445%6%32%
54935
Cloud CoverDay
16%9%47%6%35%45%6%30%
55943
Night
15%9%47%6%3445%6%32%
54940
TransparencyDay
53%5%11%18%10%1
55622
Night
51%5%12%18%10%
54764
SeeingDay
25%14%27%18%10%3
8146
Night
22%14%27%24%9%
17437

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
13%12%6%13%8%45%446%21%
1672
16th to endDay
11%12%6%13%9%45%5%45%21%
1953
February1st to 15thDay
16%12%7%11%9%35%445%18%
1845
16th to endDay
15%13%5%10%9%44445%22%
1813
March1st to 15thDay
16%13%7%8%7%3444424%
2187
16th to endDay
16%12%5%7%5%34445%29%
2540
April1st to 15thDay
18%12%5%6%5%34346%30%
2512
16th to endDay
16%10%36%5%33346%36%
2488
May1st to 15thDay
22%7%26%435%46%6%30%
2875
16th to endDay
17%7%36%5%3445%7%33%
3066
June1st to 15thDay
20%5%26%5%35%5%6%8%29%
2940
16th to endDay
15%7%25%5%345%6%9%33%
2940
July1st to 15thDay
9%5%25%7%46%5%7%9%35%
2940
16th to endDay
12%5%26%6%45%5%6%8%34%
3093
August1st to 15thDay
15%6%25%6%35%6%5%8%32%
2682
16th to endDay
13%6%25%6%35%5%6%8%35%
2678
September1st to 15thDay
18%7%26%5%35%5%47%33%
2520
16th to endDay
15%6%2442445%5%41%
2182
October1st to 15thDay
17%10%46%5%34446%32%
1950
16th to endDay
20%11%36%6%44446%26%
2033
November1st to 15thDay
17%11%36%5%33346%33%
1851
16th to endDay
18%13%46%6%24346%27%
1701
December1st to 15thDay
15%16%7%9%6%35%445%20%
1680
16th to endDay
17%16%8%11%7%3443416%
1792
January1st to 15thNight
14%11%411%7%36%46%6%20%
2926
16th to endNight
13%12%410%9%5%5%45%6%22%
2972
February1st to 15thNight
14%11%6%11%9%36%45%421%
2675
16th to endNight
16%11%5%10%7%35%445%24%
2232
March1st to 15thNight
16%12%5%8%6%3434427%
2408
16th to endNight
15%11%47%42445%5%34%
2388
April1st to 15thNight
19%10%46%6%14446%31%
2096
16th to endNight
19%7%25%423345%40%
2077
May1st to 15thNight
18%7%26%6%245%46%34%
1747
16th to endNight
12%6%36%4445%5%7%38%
1751
June1st to 15thNight
19%6%3442335%8%37%
1680
16th to endNight
10%3245%35%5%5%8%44%
1680
July1st to 15thNight
7%335%436%5%6%9%44%
1680
16th to endNight
12%424425%5%7%9%43%
1776
August1st to 15thNight
9%5%25%5%445%6%8%41%
1861
16th to endNight
11%425%425%448%46%
2213
September1st to 15thNight
14%5%25%43345%6%42%
2100
16th to endNight
13%414425%45%7%45%
2130
October1st to 15thNight
17%7%35%424346%37%
2340
16th to endNight
21%10%36%6%2345%6%30%
2541
November1st to 15thNight
15%10%46%5%3445%6%33%
2667
16th to endNight
16%12%36%5%345%46%30%
2919
December1st to 15thNight
18%13%5%9%6%35%46%5%21%
2940
16th to endNight
17%14%7%10%7%35%5%45%17%
3136

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
13%12%6%13%8%34445%21%
1672
16th to endDay
11%12%7%13%9%35%5%4421%
1953
February1st to 15thDay
17%12%6%11%9%36%44419%
1845
16th to endDay
15%13%5%10%8%3444424%
1813
March1st to 15thDay
16%14%6%9%7%3444424%
2198
16th to endDay
16%13%5%7%5%25%445%29%
2539
April1st to 15thDay
17%13%5%6%5%24446%29%
2512
16th to endDay
16%10%46%5%23445%36%
2488
May1st to 15thDay
21%8%35%5%25%5%5%6%30%
2875
16th to endDay
16%7%26%6%35%45%8%32%
3066
June1st to 15thDay
20%6%25%6%36%5%6%8%29%
2940
16th to endDay
15%7%35%5%345%6%9%33%
2940
July1st to 15thDay
9%5%26%7%46%6%7%9%34%
2940
16th to endDay
12%5%26%6%35%6%6%8%34%
3093
August1st to 15thDay
15%6%27%6%36%5%6%8%31%
2682
16th to endDay
13%6%36%6%35%5%6%8%35%
2678
September1st to 15thDay
18%7%36%5%35%45%6%34%
2520
16th to endDay
15%6%25%433446%41%
2182
October1st to 15thDay
16%11%36%5%34446%32%
1950
16th to endDay
20%12%36%7%34446%26%
2033
November1st to 15thDay
17%12%36%5%33346%32%
1851
16th to endDay
19%14%36%5%24445%28%
1701
December1st to 15thDay
16%16%8%9%7%33445%21%
1680
16th to endDay
17%14%9%12%7%34435%16%
1792
January1st to 15thNight
15%11%5%12%7%45%45%7%20%
2926
16th to endNight
13%11%5%10%9%5%6%445%22%
2972
February1st to 15thNight
14%11%6%11%8%45%5%45%22%
2668
16th to endNight
15%12%5%11%7%345%5%5%24%
2232
March1st to 15thNight
16%12%410%6%35%435%27%
2420
16th to endNight
15%10%47%5%24446%34%
2388
April1st to 15thNight
19%11%45%5%34446%31%
2096
16th to endNight
18%8%35%423346%39%
2077
May1st to 15thNight
19%7%26%6%345%45%34%
1747
16th to endNight
11%8%36%5%35%5%5%7%38%
1751
June1st to 15thNight
19%7%3442336%7%37%
1680
16th to endNight
11%4245%245%5%8%44%
1680
July1st to 15thNight
8%325%5%35%5%7%8%43%
1680
16th to endNight
12%4244345%7%8%42%
1776
August1st to 15thNight
9%5%25%5%346%6%8%41%
1861
16th to endNight
10%434435%45%7%45%
2213
September1st to 15thNight
14%6%25%434446%43%
2100
16th to endNight
14%425%33345%6%45%
2130
October1st to 15thNight
17%7%35%5%2435%6%37%
2340
16th to endNight
21%11%26%5%3425%6%30%
2541
November1st to 15thNight
15%11%36%5%3445%6%33%
2667
16th to endNight
17%11%45%5%25%45%6%30%
2919
December1st to 15thNight
17%13%6%9%6%34446%22%
2940
16th to endNight
17%13%7%11%7%36%5%45%17%
3136

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
64%410%13%5%1
1673
16th to endDay
64%412%11%6%
1953
February1st to 15thDay
67%5%8%12%6%
1847
16th to endDay
63%39%15%6%
1813
March1st to 15thDay
62%5%11%13%6%
2198
16th to endDay
56%48%17%12%1
2540
April1st to 15thDay
55%5%8%19%9%1
2512
16th to endDay
50%48%19%14%2
2488
May1st to 15thDay
53%5%9%20%9%1
2875
16th to endDay
49%7%11%20%10%
3070
June1st to 15thDay
52%6%10%20%10%
2940
16th to endDay
46%5%12%21%11%1
2940
July1st to 15thDay
44%7%12%20%13%1
2791
16th to endDay
44%7%14%20%11%
2926
August1st to 15thDay
48%7%12%19%10%
2669
16th to endDay
45%5%11%24%12%
2678
September1st to 15thDay
49%5%11%20%12%1
2520
16th to endDay
42%5%9%23%17%1
2182
October1st to 15thDay
52%5%9%18%12%
1950
16th to endDay
58%412%17%7%
2033
November1st to 15thDay
52%413%16%9%2
1851
16th to endDay
57%412%16%7%
1701
December1st to 15thDay
66%412%12%4
1680
16th to endDay
70%411%9%2
1792
January1st to 15thNight
62%413%11%6%
2926
16th to endNight
62%412%14%6%
2972
February1st to 15thNight
63%411%13%5%
2677
16th to endNight
60%312%14%7%1
2232
March1st to 15thNight
59%411%16%7%
2420
16th to endNight
50%410%19%12%1
2388
April1st to 15thNight
54%310%18%11%1
2096
16th to endNight
46%310%20%16%2
2077
May1st to 15thNight
50%6%9%19%13%1
1747
16th to endNight
43%7%12%22%12%1
1753
June1st to 15thNight
46%5%10%24%12%
1680
16th to endNight
36%6%15%26%13%1
1680
July1st to 15thNight
35%8%13%24%16%1
1600
16th to endNight
36%7%16%24%13%2
1680
August1st to 15thNight
39%7%14%26%11%
1850
16th to endNight
37%5%13%26%15%
2213
September1st to 15thNight
41%5%13%23%13%1
2100
16th to endNight
37%5%10%27%18%
2130
October1st to 15thNight
47%6%11%20%13%1
2340
16th to endNight
54%414%18%7%
2541
November1st to 15thNight
50%412%17%11%2
2667
16th to endNight
53%6%13%18%8%
2919
December1st to 15thNight
62%6%13%12%4
2940
16th to endNight
67%5%12%11%2
3136

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
27%28%32%5%5%
120
16th to endDay
31%26%32%8%1
174
February1st to 15thDay
32%31%28%6%
180
16th to endDay
32%28%27%9%1
316
March1st to 15thDay
32%19%31%12%5%
390
16th to endDay
29%21%27%13%42
416
April1st to 15thDay
34%20%27%12%41
390
16th to endDay
27%19%25%13%10%2
379
May1st to 15thDay
33%16%25%12%10%2
408
16th to endDay
22%11%29%21%10%3
459
June1st to 15thDay
24%12%28%22%11%
435
16th to endDay
23%9%31%21%11%1
435
July1st to 15thDay
12%5%26%30%18%5%
425
16th to endDay
19%228%26%16%5%
454
August1st to 15thDay
20%5%25%22%18%8%
418
16th to endDay
15%6%22%28%15%12%
460
September1st to 15thDay
20%9%24%19%18%8%
435
16th to endDay
17%7%24%21%16%12%
378
October1st to 15thDay
26%8%24%21%15%3
375
16th to endDay
28%20%29%14%6%
385
November1st to 15thDay
29%12%22%21%11%
325
16th to endDay
37%18%29%10%3
141
December1st to 15thDay
25%23%30%14%5%1
120
16th to endDay
33%31%25%10%
128
January1st to 15thNight
25%23%30%17%3
840
16th to endNight
22%20%37%18%1
896
February1st to 15thNight
26%22%34%15%1
824
16th to endNight
29%19%32%16%2
735
March1st to 15thNight
28%22%28%18%2
840
16th to endNight
22%19%31%19%5%
896
April1st to 15thNight
28%18%30%19%2
838
16th to endNight
25%15%29%19%9%
831
May1st to 15thNight
23%10%28%28%8%
487
16th to endNight
13%9%32%31%11%1
439
June1st to 15thNight
21%9%23%31%12%
420
16th to endNight
12%425%44%12%
420
July1st to 15thNight
9%321%45%18%1
400
16th to endNight
14%218%42%19%2
446
August1st to 15thNight
12%219%37%25%2
620
16th to endNight
13%317%34%28%2
875
September1st to 15thNight
19%5%21%32%19%2
840
16th to endNight
16%7%20%27%21%5%
782
October1st to 15thNight
21%10%25%26%15%1
780
16th to endNight
29%15%28%22%4
832
November1st to 15thNight
22%15%31%21%7%
820
16th to endNight
27%17%28%20%4
840
December1st to 15thNight
26%20%28%19%3
840
16th to endNight
28%21%31%15%2
896
Page generated at 2019-09-17 21:12:14. Version ac04

Copyright 2019 A. Danko


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