Halbmond Observatorium
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Halbmond Observatorium clear sky chart from 2005-11-05 to 2017-10-16.

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
47%
15748
26%
47448
18%
15703
56%
15703
32%
27834

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
30%
899
28%
2327
10%
895
42%
895
28%
1494
January16th to endNight
27%
960
28%
2496
9%
960
39%
960
31%
1582
February1st to 15thNight
24%
858
21%
2267
7%
855
33%
855
28%
1465
February16th to endNight
26%
604
29%
1866
11%
604
41%
604
27%
1100
March1st to 15thNight
29%
540
23%
1980
15%
540
40%
540
21%
1208
March16th to endNight
34%
576
21%
2112
15%
576
44%
576
23%
1274
April1st to 15thNight
33%
539
26%
1800
14%
539
50%
539
30%
988
April16th to endNight
37%
540
25%
1800
18%
540
51%
540
30%
1020
May1st to 15thNight
50%
540
20%
1758
17%
540
58%
540
28%
1057
May16th to endNight
50%
563
23%
1685
17%
561
58%
561
33%
1013
June1st to 15thNight
74%
540
24%
1509
21%
540
78%
540
48%
821
June16th to endNight
74%
540
26%
1589
25%
540
77%
540
45%
844
July1st to 15thNight
72%
510
18%
1530
18%
510
75%
510
36%
881
July16th to endNight
84%
564
26%
1594
29%
531
84%
531
44%
847
August1st to 15thNight
79%
539
25%
1661
28%
536
81%
536
43%
869
August16th to endNight
74%
573
25%
1910
31%
573
75%
573
32%
1100
September1st to 15thNight
70%
540
26%
1800
29%
540
72%
540
34%
1007
September16th to endNight
68%
594
34%
1973
32%
594
72%
594
38%
1053
October1st to 15thNight
57%
720
31%
2160
23%
720
62%
720
39%
1195
October16th to endNight
51%
708
36%
2124
23%
708
62%
708
40%
1143
November1st to 15thNight
49%
700
31%
2100
22%
700
58%
700
35%
1180
November16th to endNight
39%
741
29%
2325
19%
741
51%
741
29%
1372
December1st to 15thNight
35%
900
22%
2520
11%
900
44%
900
27%
1633
December16th to endNight
32%
960
24%
2562
12%
960
41%
960
26%
1688

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
13%5%24435%45%7%44%
47931
Night
12%424423346%50%
47644
TransparencyDay
39%410%22%18%4
47632
Night
34%39%23%22%6%
47448
SeeingDay
12%5%20%27%24%8%
5787
Night
14%8%24%30%19%2
15749

By Month

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
19%42432334447%
1611
16th to endDay
17%6%3432334447%
1728
February1st to 15thDay
18%6%24313345%45%
1592
16th to endDay
18%6%35%5%2424441%
1616
March1st to 15thDay
20%6%345%24335%41%
1980
16th to endDay
16%7%36%5%34346%39%
2110
April1st to 15thDay
13%5%35%323347%47%
2147
16th to endDay
16%5%25%43435%5%42%
2160
May1st to 15thDay
17%6%25%5%34446%38%
2190
16th to endDay
10%5%26%6%47%6%6%7%35%
2430
June1st to 15thDay
7%3245%46%6%6%7%44%
2438
16th to endDay
5%3146%47%6%7%10%41%
2358
July1st to 15thDay
7%5%35%6%47%6%8%10%35%
2340
16th to endDay
5%3246%47%6%8%9%42%
2466
August1st to 15thDay
7%415%6%38%7%7%9%38%
2288
16th to endDay
9%435%6%36%6%6%8%39%
2292
September1st to 15thDay
13%5%145%3346%6%44%
2160
16th to endDay
11%313424446%51%
1970
October1st to 15thDay
12%5%24323345%51%
1800
16th to endDay
15%212212235%59%
1769
November1st to 15thDay
12%423312346%57%
1758
16th to endDay
15%7%25%423225%48%
1629
December1st to 15thDay
20%7%24323335%43%
1440
16th to endDay
19%6%3441343442%
1659
January1st to 15thNight
17%6%2331223351%
2327
16th to endNight
17%5%2432333450%
2496
February1st to 15thNight
19%7%24313336%45%
2258
16th to endNight
15%5%23313335%51%
1866
March1st to 15thNight
19%5%24424335%44%
1980
16th to endNight
13%6%346%24345%45%
2112
April1st to 15thNight
10%3145%2346%8%51%
1800
16th to endNight
10%425%323446%50%
1800
May1st to 15thNight
13%5%13434446%47%
1757
16th to endNight
9%426%5%2435%9%45%
1683
June1st to 15thNight
321342446%9%57%
1509
16th to endNight
431232445%9%56%
1589
July1st to 15thNight
32146%35%6%7%11%44%
1620
16th to endNight
3113425%5%6%13%52%
1702
August1st to 15thNight
42133345%6%12%51%
1671
16th to endNight
6%3244446%7%9%45%
1910
September1st to 15thNight
9%414323447%53%
1800
16th to endNight
7%3144235%46%56%
1973
October1st to 15thNight
9%314423345%56%
2160
16th to endNight
12%31332222462%
2124
November1st to 15thNight
10%314323446%56%
2100
16th to endNight
16%5%2332333451%
2325
December1st to 15thNight
18%6%25%422345%45%
2520
16th to endNight
18%6%24323335%45%
2562

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
41%25%24%20%5%
1612
16th to endDay
41%25%23%22%4
1728
February1st to 15thDay
40%39%24%18%4
1594
16th to endDay
47%26%20%18%4
1616
March1st to 15thDay
46%38%17%17%6%
1980
16th to endDay
45%310%23%14%1
2112
April1st to 15thDay
36%410%23%19%5%
2147
16th to endDay
42%48%21%19%3
2160
May1st to 15thDay
46%5%9%16%19%3
2190
16th to endDay
42%6%14%22%12%1
2434
June1st to 15thDay
35%6%11%26%19%1
2438
16th to endDay
34%6%12%24%18%2
2358
July1st to 15thDay
38%7%14%24%13%1
2201
16th to endDay
33%7%15%26%14%1
2311
August1st to 15thDay
36%7%14%24%14%2
2274
16th to endDay
39%7%14%21%14%3
2292
September1st to 15thDay
38%5%10%19%18%7%
2160
16th to endDay
32%39%23%24%7%
1970
October1st to 15thDay
34%39%21%22%8%
1800
16th to endDay
28%3323%28%11%
1769
November1st to 15thDay
29%28%24%26%8%
1758
16th to endDay
41%26%19%24%6%
1629
December1st to 15thDay
43%38%22%14%6%
1440
16th to endDay
45%29%20%17%4
1659
January1st to 15thNight
39%25%21%26%4
2327
16th to endNight
38%16%23%22%6%
2496
February1st to 15thNight
41%27%23%19%6%
2267
16th to endNight
36%26%25%19%8%
1866
March1st to 15thNight
43%28%16%19%8%
1980
16th to endNight
41%28%23%20%2
2112
April1st to 15thNight
31%310%23%21%9%
1800
16th to endNight
33%49%23%24%4
1800
May1st to 15thNight
37%410%21%18%6%
1758
16th to endNight
34%416%26%16%1
1685
June1st to 15thNight
22%5%13%32%24%2
1509
16th to endNight
23%5%12%28%24%5%
1589
July1st to 15thNight
27%9%17%27%15%2
1530
16th to endNight
22%7%16%32%18%2
1594
August1st to 15thNight
23%5%17%31%18%2
1661
16th to endNight
32%6%13%26%17%3
1910
September1st to 15thNight
30%6%10%24%21%7%
1800
16th to endNight
27%48%23%26%9%
1973
October1st to 15thNight
29%38%22%23%12%
2160
16th to endNight
29%1419%32%12%
2124
November1st to 15thNight
30%36%22%25%11%
2100
16th to endNight
37%25%18%28%6%
2325
December1st to 15thNight
42%28%20%18%6%
2520
16th to endNight
43%27%21%19%5%
2562

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
23%13%40%14%7%1
90
16th to endDay
20%25%37%11%5%
96
February1st to 15thDay
23%13%44%14%22
90
16th to endDay
22%20%34%18%21
81
March1st to 15thDay
33%15%41%5%4
90
16th to endDay
12%29%19%33%5%
96
April1st to 15thDay
18%13%34%21%10%1
266
16th to endDay
23%8%28%23%14%2
270
May1st to 15thDay
17%10%32%24%12%3
327
16th to endDay
12%6%26%30%17%5%
517
June1st to 15thDay
7%116%35%30%9%
495
16th to endDay
5%319%32%28%9%
495
July1st to 15thDay
6%216%35%30%8%
475
16th to endDay
5%5%30%38%19%
515
August1st to 15thDay
8%19%31%34%15%
441
16th to endDay
15%9%23%36%15%
332
September1st to 15thDay
12%19%22%41%12%
315
16th to endDay
10%116%33%28%9%
196
October1st to 15thDay
10%5%28%34%17%4
135
16th to endDay
19%5%24%35%11%5%
99
November1st to 15thDay
17%8%27%21%21%3
90
16th to endDay
27%14%27%21%6%2
90
December1st to 15thDay
23%13%26%20%13%3
90
16th to endDay
29%15%41%9%4
96
January1st to 15thNight
22%15%28%26%6%
900
16th to endNight
19%13%36%26%3
960
February1st to 15thNight
23%13%35%24%3
858
16th to endNight
20%15%35%25%3
604
March1st to 15thNight
20%11%35%27%4
540
16th to endNight
17%10%32%29%9%
576
April1st to 15thNight
13%12%37%25%9%
539
16th to endNight
11%10%36%28%11%
540
May1st to 15thNight
16%6%23%39%12%1
540
16th to endNight
12%326%31%23%2
563
June1st to 15thNight
3112%41%37%3
540
16th to endNight
5%210%42%34%5%
540
July1st to 15thNight
2112%33%45%5%
510
16th to endNight
3430%50%10%
564
August1st to 15thNight
417%31%44%11%
539
16th to endNight
8%16%32%44%6%
573
September1st to 15thNight
10%110%28%43%5%
540
16th to endNight
9%114%31%37%4
594
October1st to 15thNight
11%321%30%29%3
720
16th to endNight
13%6%25%33%20%1
708
November1st to 15thNight
11%10%25%33%18%1
700
16th to endNight
19%11%26%27%15%
741
December1st to 15thNight
22%8%30%30%8%
900
16th to endNight
22%12%29%29%6%
960
Page generated at 2017-10-17 15:35:20. Version ac04

Copyright 2017 A. Danko


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