Goethe Link Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Goethe Link Observatory clear sky chart from 2005-11-05 to

2017-09-12
.

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
41%
15774
19%
46751
13%
15731
47%
15731
24%
31150

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
21%
900
14%
2506
6%
895
29%
895
16%
1901
January16th to endNight
20%
915
13%
2625
6%
915
26%
915
16%
1982
February1st to 15thNight
21%
703
13%
2112
5%
701
28%
701
16%
1522
February16th to endNight
23%
631
16%
1893
7%
631
31%
631
16%
1371
March1st to 15thNight
28%
720
14%
2152
9%
720
33%
720
17%
1543
March16th to endNight
31%
705
16%
2049
9%
705
38%
705
21%
1447
April1st to 15thNight
32%
539
18%
1797
10%
539
44%
539
22%
1160
April16th to endNight
36%
540
21%
1709
12%
540
46%
540
25%
1085
May1st to 15thNight
37%
540
15%
1620
9%
540
43%
540
21%
1146
May16th to endNight
54%
561
17%
1642
13%
561
58%
561
29%
1076
June1st to 15thNight
60%
540
18%
1440
14%
540
62%
540
37%
882
June16th to endNight
64%
540
20%
1440
15%
540
68%
540
37%
894
July1st to 15thNight
67%
510
17%
1360
14%
510
69%
510
38%
835
July16th to endNight
77%
564
25%
1461
20%
531
79%
531
46%
811
August1st to 15thNight
73%
539
22%
1630
20%
536
75%
536
37%
935
August16th to endNight
74%
573
24%
1910
26%
573
78%
573
37%
1032
September1st to 15thNight
65%
588
26%
1825
25%
588
68%
588
33%
1062
September16th to endNight
61%
657
26%
1815
20%
657
64%
657
34%
1123
October1st to 15thNight
53%
660
31%
1815
23%
660
61%
660
36%
1086
October16th to endNight
34%
704
21%
2261
15%
704
44%
704
24%
1432
November1st to 15thNight
41%
700
26%
2276
19%
700
52%
700
28%
1324
November16th to endNight
33%
720
19%
2340
13%
720
41%
720
19%
1575
December1st to 15thNight
23%
765
12%
2385
8%
765
28%
765
15%
1799
December16th to endNight
19%
960
12%
2688
4%
960
27%
960
13%
2127

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
14%7%36%5%3445%7%38%
47905
Night
14%7%36%5%24446%40%
46924
Cloud CoverDay
14%7%36%5%3445%7%38%
47914
Night
14%7%36%424446%40%
46929
TransparencyDay
44%5%11%21%13%2
47597
Night
44%5%10%21%14%2
46751
SeeingDay
15%6%23%25%20%9%
5794
Night
17%8%25%30%15%2
15777

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%10%5%8%7%34335%28%
1432
16th to endDay
11%14%6%8%6%34345%30%
1593
February1st to 15thDay
15%11%5%9%5%34445%30%
1750
16th to endDay
14%12%49%5%3435%6%30%
1580
March1st to 15thDay
21%9%35%6%34445%31%
1796
16th to endDay
16%9%47%5%2445%7%31%
2184
April1st to 15thDay
17%7%35%42445%6%38%
2151
16th to endDay
18%6%27%433346%37%
2250
May1st to 15thDay
21%7%37%5%2445%6%32%
2331
16th to endDay
11%5%26%5%36%5%7%7%37%
2470
June1st to 15thDay
10%5%245%345%5%8%44%
2520
16th to endDay
8%5%245%35%5%6%10%41%
2520
July1st to 15thDay
11%425%5%35%5%6%9%39%
2520
16th to endDay
6%3146%36%6%8%10%42%
2607
August1st to 15thDay
8%4245%26%5%7%10%42%
2317
16th to endDay
7%425%5%45%5%7%8%44%
2292
September1st to 15thDay
12%424436%5%6%7%41%
2041
16th to endDay
13%4245%2445%6%47%
1815
October1st to 15thDay
14%5%25%4345%46%44%
1815
16th to endDay
15%8%25%434446%39%
1611
November1st to 15thDay
11%425%424446%50%
1582
16th to endDay
18%10%47%434345%35%
1620
December1st to 15thDay
20%13%47%433446%28%
1572
16th to endDay
20%14%5%7%5%23336%27%
1536
January1st to 15thNight
19%10%47%6%34445%29%
2506
16th to endNight
15%13%6%8%6%3434429%
2625
February1st to 15thNight
16%10%5%8%6%23345%31%
2110
16th to endNight
15%11%47%5%35%345%32%
1893
March1st to 15thNight
17%9%45%6%34445%34%
2139
16th to endNight
17%7%36%6%34447%35%
2049
April1st to 15thNight
14%7%36%5%24445%41%
1797
16th to endNight
14%5%36%424446%42%
1709
May1st to 15thNight
18%7%36%5%24448%33%
1620
16th to endNight
10%5%25%5%246%6%9%40%
1640
June1st to 15thNight
8%43442445%8%50%
1440
16th to endNight
7%314435%5%6%9%47%
1440
July1st to 15thNight
8%4234245%6%9%49%
1440
16th to endNight
5%22323335%10%55%
1560
August1st to 15thNight
6%2135%25%5%6%8%51%
1641
16th to endNight
6%2144335%6%8%53%
1910
September1st to 15thNight
9%5%2432345%6%51%
1825
16th to endNight
10%5%25%424447%49%
1815
October1st to 15thNight
9%3244235%5%6%52%
1815
16th to endNight
18%6%25%323346%43%
2261
November1st to 15thNight
11%7%25%323446%48%
2276
16th to endNight
18%9%45%433346%36%
2340
December1st to 15thNight
21%12%5%9%5%23335%27%
2385
16th to endNight
23%13%47%5%2433425%
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%10%5%8%6%3433428%
1432
16th to endDay
11%13%7%7%6%34346%30%
1593
February1st to 15thDay
15%11%5%9%5%34445%30%
1750
16th to endDay
14%12%49%5%34347%30%
1580
March1st to 15thDay
21%9%36%5%34445%31%
1806
16th to endDay
16%10%47%5%2445%7%31%
2183
April1st to 15thDay
17%7%25%5%2345%6%38%
2151
16th to endDay
18%6%26%5%2345%6%37%
2250
May1st to 15thDay
21%7%26%5%24446%33%
2331
16th to endDay
11%6%25%6%35%5%7%8%37%
2470
June1st to 15thDay
10%5%245%335%5%8%44%
2520
16th to endDay
9%5%24435%5%6%10%42%
2520
July1st to 15thDay
11%4245%35%5%6%9%39%
2520
16th to endDay
6%3246%36%6%8%9%42%
2607
August1st to 15thDay
8%4245%36%5%7%10%42%
2317
16th to endDay
7%415%5%45%47%8%44%
2292
September1st to 15thDay
12%4245%36%5%6%7%41%
2041
16th to endDay
13%425%43345%6%46%
1815
October1st to 15thDay
14%5%25%4235%46%44%
1815
16th to endDay
16%8%26%424437%39%
1611
November1st to 15thDay
11%434424446%50%
1582
16th to endDay
18%9%47%434245%35%
1620
December1st to 15thDay
21%12%47%5%24346%28%
1572
16th to endDay
20%13%5%7%5%23336%27%
1536
January1st to 15thNight
18%11%47%6%34445%29%
2506
16th to endNight
15%13%6%8%6%34345%29%
2625
February1st to 15thNight
16%10%48%6%24345%32%
2103
16th to endNight
15%11%48%5%24345%32%
1893
March1st to 15thNight
18%9%36%5%34435%34%
2152
16th to endNight
17%8%26%5%34447%35%
2049
April1st to 15thNight
15%6%36%5%24445%41%
1797
16th to endNight
14%5%36%424446%42%
1709
May1st to 15thNight
18%7%46%5%33447%34%
1619
16th to endNight
10%5%25%5%345%6%9%40%
1640
June1st to 15thNight
8%43442445%7%50%
1440
16th to endNight
6%324435%5%6%10%47%
1440
July1st to 15thNight
8%4234145%5%9%49%
1440
16th to endNight
5%22323336%9%56%
1560
August1st to 15thNight
6%2135%35%5%5%8%51%
1641
16th to endNight
6%2134245%6%8%53%
1910
September1st to 15thNight
9%5%2432335%6%51%
1825
16th to endNight
10%5%25%323447%49%
1815
October1st to 15thNight
9%32442345%6%52%
1815
16th to endNight
18%6%24323345%43%
2261
November1st to 15thNight
11%7%2442345%6%48%
2276
16th to endNight
19%8%45%423346%36%
2340
December1st to 15thNight
21%11%5%9%423335%27%
2385
16th to endNight
24%13%46%5%3433425%
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
58%49%16%10%
1433
16th to endDay
54%412%20%6%
1593
February1st to 15thDay
55%5%10%18%9%
1752
16th to endDay
55%5%10%21%7%
1580
March1st to 15thDay
54%5%10%20%8%
1806
16th to endDay
51%5%13%21%6%
2184
April1st to 15thDay
45%410%24%14%
2151
16th to endDay
46%5%9%21%11%5%
2250
May1st to 15thDay
51%6%10%19%11%
2331
16th to endDay
42%8%12%19%15%2
2474
June1st to 15thDay
36%7%10%26%16%2
2520
16th to endDay
36%6%14%21%16%3
2520
July1st to 15thDay
40%6%11%20%17%2
2371
16th to endDay
33%8%16%26%13%2
2444
August1st to 15thDay
33%7%13%24%18%2
2304
16th to endDay
34%8%11%23%16%6%
2292
September1st to 15thDay
39%5%9%21%18%4
2041
16th to endDay
36%5%8%23%24%2
1815
October1st to 15thDay
39%5%9%23%20%2
1815
16th to endDay
44%410%23%14%1
1611
November1st to 15thDay
35%410%23%20%5%
1582
16th to endDay
51%38%21%13%1
1620
December1st to 15thDay
57%410%18%8%
1572
16th to endDay
58%5%10%18%5%1
1536
January1st to 15thNight
57%48%19%9%
2506
16th to endNight
57%411%18%7%
2625
February1st to 15thNight
54%413%19%7%
2112
16th to endNight
54%411%20%9%
1893
March1st to 15thNight
51%5%9%20%10%2
2152
16th to endNight
49%412%23%8%1
2049
April1st to 15thNight
44%49%23%15%2
1797
16th to endNight
41%49%22%15%6%
1709
May1st to 15thNight
49%6%10%20%11%1
1620
16th to endNight
38%7%14%19%14%5%
1642
June1st to 15thNight
32%6%10%27%21%2
1440
16th to endNight
31%7%13%22%20%4
1440
July1st to 15thNight
30%6%15%21%20%4
1360
16th to endNight
24%5%14%33%18%3
1461
August1st to 15thNight
28%7%15%23%21%3
1630
16th to endNight
26%7%12%26%20%6%
1910
September1st to 15thNight
32%5%9%23%22%6%
1825
16th to endNight
34%5%7%21%26%4
1815
October1st to 15thNight
31%5%8%26%23%4
1815
16th to endNight
43%39%27%14%2
2261
November1st to 15thNight
36%39%22%22%5%
2276
16th to endNight
49%310%21%14%
2340
December1st to 15thNight
60%39%16%9%
2385
16th to endNight
62%5%7%15%8%
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
35%12%27%18%41
90
16th to endDay
13%27%38%19%1
96
February1st to 15thDay
22%23%35%14%4
90
16th to endDay
16%14%41%20%6%
81
March1st to 15thDay
29%16%35%16%2
96
16th to endDay
20%13%31%23%9%1
288
April1st to 15thDay
19%12%27%27%12%1
270
16th to endDay
21%7%27%24%14%5%
270
May1st to 15thDay
25%8%26%23%12%4
288
16th to endDay
16%426%25%17%10%
370
June1st to 15thDay
10%5%21%33%22%6%
495
16th to endDay
12%5%28%28%18%7%
495
July1st to 15thDay
14%320%28%21%12%
475
16th to endDay
5%112%30%32%17%
467
August1st to 15thDay
12%7%22%32%23%
313
16th to endDay
7%13%22%36%18%
332
September1st to 15thDay
11%113%29%30%14%
299
16th to endDay
14%314%20%34%12%
254
October1st to 15thDay
12%5%23%25%25%7%
255
16th to endDay
18%9%36%30%4
104
November1st to 15thDay
8%10%22%25%26%6%
90
16th to endDay
31%10%35%13%10%
90
December1st to 15thDay
22%13%40%16%6%1
90
16th to endDay
23%17%45%11%1
96
January1st to 15thNight
23%14%35%22%3
900
16th to endNight
21%15%34%24%3
915
February1st to 15thNight
22%14%35%25%2
704
16th to endNight
21%12%36%25%3
631
March1st to 15thNight
22%14%30%27%5%
720
16th to endNight
20%8%32%29%7%
705
April1st to 15thNight
17%11%34%28%7%
539
16th to endNight
17%6%33%29%11%1
540
May1st to 15thNight
18%7%27%35%10%
540
16th to endNight
11%322%35%22%4
563
June1st to 15thNight
10%219%45%22%1
540
16th to endNight
9%119%42%26%1
540
July1st to 15thNight
10%12%39%33%2
510
16th to endNight
6%17%38%40%6%
564
August1st to 15thNight
7%19%38%36%7%
539
16th to endNight
7%9%34%41%6%
573
September1st to 15thNight
11%213%37%29%5%
588
16th to endNight
13%413%32%31%4
657
October1st to 15thNight
11%6%21%33%21%5%
660
16th to endNight
22%8%32%26%10%
704
November1st to 15thNight
14%10%29%29%14%2
700
16th to endNight
23%12%25%28%9%
720
December1st to 15thNight
27%10%30%22%6%1
765
16th to endNight
31%9%32%21%5%
960
Page generated at 2017-09-13 07:39:17. Version ac04

Copyright 2017 A. Danko


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