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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 2020-06-03.

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%
18414
14%
57828
8%
18382
36%
18382
16%
41192

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
15%
900
9%
3136
5%
896
22%
896
9%
2417
January16th to endNight
14%
960
10%
3185
4%
960
23%
960
9%
2440
February1st to 15thNight
11%
884
8%
2872
2%
881
19%
881
8%
2275
February16th to endNight
15%
791
13%
2402
6%
791
25%
791
12%
1827
March1st to 15thNight
17%
900
12%
2592
6%
900
25%
900
13%
1981
March16th to endNight
20%
960
18%
2558
6%
960
29%
960
18%
1857
April1st to 15thNight
19%
898
13%
2246
4%
898
24%
898
18%
1697
April16th to endNight
26%
891
16%
2227
4%
891
32%
891
23%
1569
May1st to 15thNight
29%
521
16%
1871
10%
521
39%
521
15%
1307
May16th to endNight
38%
470
16%
1881
14%
470
47%
470
17%
1201
June1st to 15thNight
38%
425
16%
1701
15%
425
48%
425
17%
1093
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%
837
25%
2279
18%
837
54%
837
33%
1457
October1st to 15thNight
35%
840
17%
2520
13%
840
42%
840
20%
1733
October16th to endNight
22%
896
14%
2736
6%
896
31%
896
16%
1980
November1st to 15thNight
23%
880
16%
2862
8%
880
34%
880
17%
1984
November16th to endNight
22%
900
14%
3127
8%
900
31%
900
13%
2249
December1st to 15thNight
18%
900
8%
3150
5%
900
23%
900
8%
2457
December16th to endNight
14%
960
8%
3360
3%
960
21%
960
7%
2674

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%
58591
Night
15%9%47%6%3445%6%32%
57999
Cloud CoverDay
16%10%47%6%3445%6%30%
58601
Night
15%9%47%6%3445%6%32%
58004
TransparencyDay
53%5%11%18%10%1
58280
Night
52%5%12%18%10%
57828
SeeingDay
26%15%27%17%10%3
9010
Night
23%14%28%24%9%
18415

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%11%6%13%8%35%446%21%
1792
16th to endDay
11%12%6%13%8%45%5%4421%
2092
February1st to 15thDay
17%12%7%11%9%35%445%18%
1980
16th to endDay
15%12%5%11%9%44445%23%
1951
March1st to 15thDay
16%13%7%8%7%3444425%
2344
16th to endDay
17%12%5%7%5%34445%28%
2722
April1st to 15thDay
18%12%5%6%5%34446%29%
2692
16th to endDay
16%10%36%5%34346%35%
2668
May1st to 15thDay
21%7%25%5%35%46%6%30%
3082
16th to endDay
16%7%26%5%3445%7%33%
3290
June1st to 15thDay
20%5%26%5%35%5%6%8%29%
2968
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%43%
2338
October1st to 15thDay
17%9%37%5%34446%33%
2100
16th to endDay
21%12%36%6%44446%26%
2190
November1st to 15thDay
17%11%27%5%33446%32%
1986
16th to endDay
18%14%46%6%24346%27%
1823
December1st to 15thDay
17%15%7%9%6%35%445%20%
1800
16th to endDay
17%16%8%11%8%4443417%
1920
January1st to 15thNight
14%11%5%11%7%36%45%6%20%
3136
16th to endNight
12%11%5%10%9%5%5%5%5%6%21%
3185
February1st to 15thNight
16%11%6%11%9%36%44420%
2870
16th to endNight
16%11%5%10%7%35%445%25%
2402
March1st to 15thNight
16%12%5%8%6%3435%5%27%
2580
16th to endNight
16%11%47%423445%34%
2558
April1st to 15thNight
19%10%46%6%14446%30%
2246
16th to endNight
19%8%25%423345%40%
2227
May1st to 15thNight
18%8%26%6%245%46%33%
1871
16th to endNight
12%6%36%4445%5%7%38%
1879
June1st to 15thNight
19%6%3442335%8%37%
1701
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%41442445%7%46%
2279
October1st to 15thNight
18%7%35%424346%37%
2520
16th to endNight
21%10%26%6%2345%6%30%
2736
November1st to 15thNight
14%10%46%5%3445%6%34%
2862
16th to endNight
16%12%36%5%345%46%30%
3127
December1st to 15thNight
18%13%5%9%6%3446%5%21%
3150
16th to endNight
17%13%7%10%6%35%5%45%18%
3360

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%11%6%12%8%34445%21%
1792
16th to endDay
11%13%6%13%9%35%5%4421%
2092
February1st to 15thDay
18%12%6%11%8%35%44419%
1980
16th to endDay
15%13%5%10%8%3444424%
1951
March1st to 15thDay
16%14%6%9%7%3344425%
2355
16th to endDay
16%13%5%7%5%24445%29%
2721
April1st to 15thDay
17%13%46%6%24446%29%
2692
16th to endDay
16%10%46%5%23445%35%
2668
May1st to 15thDay
20%8%35%5%25%5%5%6%30%
3082
16th to endDay
16%7%26%6%35%5%5%8%32%
3290
June1st to 15thDay
20%6%25%6%36%5%6%8%29%
2968
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
14%6%25%433446%42%
2338
October1st to 15thDay
16%11%36%5%34447%33%
2100
16th to endDay
20%12%36%7%34446%26%
2190
November1st to 15thDay
17%12%37%5%33446%32%
1986
16th to endDay
18%14%36%5%24446%28%
1823
December1st to 15thDay
17%16%8%9%6%33445%20%
1800
16th to endDay
17%14%8%12%7%34435%17%
1920
January1st to 15thNight
14%11%5%12%7%45%45%7%20%
3136
16th to endNight
12%11%5%10%10%46%45%5%22%
3185
February1st to 15thNight
16%12%6%11%8%45%445%21%
2863
16th to endNight
15%12%411%7%345%5%5%24%
2402
March1st to 15thNight
16%12%410%6%34435%27%
2592
16th to endNight
15%11%5%7%424445%34%
2558
April1st to 15thNight
19%11%46%5%34446%30%
2246
16th to endNight
18%8%35%423346%39%
2227
May1st to 15thNight
18%8%26%6%345%45%33%
1871
16th to endNight
11%8%36%435%5%5%7%37%
1879
June1st to 15thNight
19%6%3442336%7%37%
1701
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
13%425%32345%7%46%
2279
October1st to 15thNight
18%7%35%5%2435%6%37%
2520
16th to endNight
21%11%26%5%3425%6%31%
2736
November1st to 15thNight
15%11%36%5%3445%6%33%
2862
16th to endNight
16%12%45%5%25%45%6%30%
3127
December1st to 15thNight
18%13%5%10%6%34446%21%
3150
16th to endNight
16%13%7%10%7%36%5%46%18%
3360

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%6%1
1793
16th to endDay
64%412%11%7%
2092
February1st to 15thDay
68%5%8%12%5%
1982
16th to endDay
62%39%15%7%
1951
March1st to 15thDay
61%410%14%7%1
2355
16th to endDay
57%48%17%12%1
2722
April1st to 15thDay
56%5%7%19%9%1
2692
16th to endDay
51%48%19%14%2
2668
May1st to 15thDay
53%5%9%20%10%1
3082
16th to endDay
49%7%11%20%10%1
3294
June1st to 15thDay
52%6%10%20%10%
2968
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
41%5%10%24%17%1
2338
October1st to 15thDay
51%5%9%19%12%1
2100
16th to endDay
58%411%17%7%
2190
November1st to 15thDay
53%413%17%9%2
1986
16th to endDay
57%412%17%7%
1823
December1st to 15thDay
66%312%11%4
1800
16th to endDay
69%411%11%3
1920
January1st to 15thNight
62%5%12%11%7%
3136
16th to endNight
62%412%14%6%
3185
February1st to 15thNight
65%411%12%5%
2872
16th to endNight
60%311%14%8%1
2402
March1st to 15thNight
59%411%17%7%
2592
16th to endNight
51%410%19%12%1
2558
April1st to 15thNight
55%310%18%11%1
2246
16th to endNight
47%310%20%15%2
2227
May1st to 15thNight
51%5%9%18%13%1
1871
16th to endNight
44%7%12%22%12%1
1881
June1st to 15thNight
46%5%10%24%12%
1701
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
36%5%10%28%18%1
2279
October1st to 15thNight
47%6%11%20%13%1
2520
16th to endNight
54%414%18%8%
2736
November1st to 15thNight
50%5%12%18%11%2
2862
16th to endNight
53%5%13%18%8%
3127
December1st to 15thNight
62%6%13%13%4
3150
16th to endNight
66%5%12%13%3
3360

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%30%30%6%4
150
16th to endDay
30%23%32%9%2
217
February1st to 15thDay
35%30%28%5%
225
16th to endDay
32%27%28%11%1
370
March1st to 15thDay
33%18%31%11%4
450
16th to endDay
31%21%28%12%32
480
April1st to 15thDay
33%20%28%12%41
450
16th to endDay
28%21%24%13%9%2
439
May1st to 15thDay
32%18%26%11%9%2
468
16th to endDay
21%12%31%20%10%3
523
June1st to 15thDay
24%13%28%21%11%
443
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
16%8%25%21%16%11%
434
October1st to 15thDay
26%8%26%21%14%3
435
16th to endDay
31%19%27%15%6%
446
November1st to 15thDay
30%14%22%20%10%
370
16th to endDay
36%16%31%11%4
173
December1st to 15thDay
30%22%29%13%41
150
16th to endDay
31%29%30%9%
160
January1st to 15thNight
25%23%30%16%3
900
16th to endNight
22%20%36%18%1
960
February1st to 15thNight
28%21%33%15%1
884
16th to endNight
29%18%33%16%2
791
March1st to 15thNight
28%22%28%18%2
900
16th to endNight
24%19%31%19%5%
960
April1st to 15thNight
28%19%30%19%2
898
16th to endNight
25%15%30%20%8%
891
May1st to 15thNight
24%10%28%27%7%
521
16th to endNight
13%9%31%32%11%1
471
June1st to 15thNight
21%9%24%31%12%
425
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%21%28%21%5%
837
October1st to 15thNight
22%9%25%26%14%1
840
16th to endNight
29%14%28%22%4
896
November1st to 15thNight
23%15%32%21%7%
880
16th to endNight
27%18%28%20%4
900
December1st to 15thNight
27%21%28%19%3
900
16th to endNight
27%21%32%16%2
960
Page generated at 2020-06-04 03:18:52. Version ac04

Copyright 2020 A. Danko


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