Broemmelsiek Park Astronomy Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Broemmelsiek Park Astronomy Area clear sky chart from 2005-11-05 to 2017-04-26.

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
37%
15421
21%
45624
12%
15374
46%
15374
26%
28872

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
23%
900
20%
2473
7%
895
33%
895
22%
1675
January16th to endNight
20%
960
20%
2496
6%
960
31%
960
23%
1725
February1st to 15thNight
21%
850
15%
2259
4%
847
28%
847
19%
1620
February16th to endNight
18%
631
21%
1893
5%
631
29%
631
22%
1225
March1st to 15thNight
20%
636
18%
2076
8%
636
30%
636
19%
1400
March16th to endNight
25%
576
14%
2046
8%
576
32%
576
15%
1407
April1st to 15thNight
27%
539
21%
1797
11%
539
42%
539
24%
1095
April16th to endNight
34%
528
23%
1760
15%
528
48%
528
27%
1057
May1st to 15thNight
37%
495
19%
1518
11%
494
46%
494
24%
986
May16th to endNight
46%
515
18%
1369
11%
513
50%
513
29%
912
June1st to 15thNight
58%
495
21%
1320
14%
495
62%
495
38%
801
June16th to endNight
60%
495
20%
1320
13%
495
64%
495
42%
775
July1st to 15thNight
63%
465
20%
1240
16%
465
65%
465
37%
759
July16th to endNight
70%
522
22%
1392
19%
489
72%
489
43%
779
August1st to 15thNight
75%
494
25%
1519
28%
491
77%
491
40%
833
August16th to endNight
73%
525
22%
1750
24%
525
76%
525
36%
948
September1st to 15thNight
61%
495
27%
1650
28%
495
65%
495
29%
957
September16th to endNight
59%
594
31%
1771
23%
594
66%
594
35%
1018
October1st to 15thNight
48%
660
29%
1980
20%
660
57%
660
34%
1138
October16th to endNight
31%
704
26%
2112
14%
704
43%
704
31%
1246
November1st to 15thNight
36%
700
28%
2273
15%
700
51%
700
31%
1252
November16th to endNight
26%
782
22%
2402
11%
782
38%
782
25%
1494
December1st to 15thNight
23%
900
16%
2520
6%
900
32%
900
19%
1796
December16th to endNight
19%
960
17%
2688
6%
960
28%
960
16%
1974

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
12%6%25%43445%7%42%
46038
Night
13%6%25%424446%45%
45808
TransparencyDay
40%6%12%23%14%2
45726
Night
39%5%11%24%16%2
45626
SeeingDay
14%9%26%26%17%5%
5221
Night
16%10%30%27%12%1
15421

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
11%8%47%6%34446%37%
1463
16th to endDay
13%9%46%5%33346%39%
1728
February1st to 15thDay
14%7%47%5%335%45%37%
1600
16th to endDay
12%9%47%435%436%38%
1580
March1st to 15thDay
16%8%46%435%345%38%
1893
16th to endDay
18%9%46%7%3445%5%31%
2175
April1st to 15thDay
14%6%25%435%445%42%
2151
16th to endDay
16%5%37%5%3445%6%36%
2111
May1st to 15thDay
19%6%35%4245%5%8%34%
2100
16th to endDay
13%425%5%345%5%8%40%
2393
June1st to 15thDay
9%4345%35%5%6%8%43%
2310
16th to endDay
6%323425%6%7%12%44%
2310
July1st to 15thDay
9%413435%5%7%10%43%
2310
16th to endDay
6%3245%35%6%6%10%46%
2361
August1st to 15thDay
7%325%5%36%6%5%10%42%
2101
16th to endDay
8%5%244345%6%9%43%
2100
September1st to 15thDay
13%4144235%5%8%44%
1980
16th to endDay
10%415%4245%5%7%49%
1844
October1st to 15thDay
14%5%25%423336%50%
1650
16th to endDay
13%5%1331334454%
1760
November1st to 15thDay
12%423323336%52%
1585
16th to endDay
16%7%24424246%41%
1557
December1st to 15thDay
16%10%26%433436%37%
1440
16th to endDay
16%11%36%423446%36%
1536
January1st to 15thNight
14%7%36%5%2443442%
2473
16th to endNight
13%9%45%424446%40%
2496
February1st to 15thNight
14%10%46%434446%35%
2250
16th to endNight
14%8%37%423335%45%
1893
March1st to 15thNight
19%7%36%42333440%
2076
16th to endNight
18%8%3443445%7%33%
2046
April1st to 15thNight
12%5%25%4245%46%45%
1797
16th to endNight
15%5%245%2335%6%45%
1760
May1st to 15thNight
16%5%2432236%7%42%
1518
16th to endNight
11%5%345%34448%44%
1368
June1st to 15thNight
7%3134345%5%8%50%
1320
16th to endNight
7%21343445%10%52%
1320
July1st to 15thNight
9%41342435%7%51%
1320
16th to endNight
431443446%11%50%
1496
August1st to 15thNight
5%22342445%8%55%
1529
16th to endNight
6%3135%3445%9%53%
1750
September1st to 15thNight
12%425%33335%6%49%
1650
16th to endNight
8%5%24423447%53%
1771
October1st to 15thNight
10%323333446%54%
1980
16th to endNight
14%6%13322335%52%
2112
November1st to 15thNight
10%5%24322246%54%
2273
16th to endNight
16%6%34313345%46%
2402
December1st to 15thNight
19%9%46%423446%33%
2520
16th to endNight
18%11%46%5%2434434%
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
47%5%8%23%13%1
1464
16th to endDay
45%5%14%24%9%1
1728
February1st to 15thDay
47%5%12%22%10%
1602
16th to endDay
47%5%10%22%12%1
1580
March1st to 15thDay
48%410%21%12%1
1893
16th to endDay
54%6%12%17%9%
2177
April1st to 15thDay
43%49%23%16%2
2151
16th to endDay
47%6%10%22%12%1
2111
May1st to 15thDay
47%7%13%21%10%
2100
16th to endDay
41%8%13%19%13%3
2397
June1st to 15thDay
35%8%12%25%15%1
2310
16th to endDay
29%8%17%24%16%3
2310
July1st to 15thDay
34%8%13%26%12%3
2161
16th to endDay
30%8%16%29%13%1
2203
August1st to 15thDay
33%8%13%25%17%1
2087
16th to endDay
35%8%11%21%18%5%
2100
September1st to 15thDay
36%6%10%21%20%4
1980
16th to endDay
33%5%9%28%20%3
1844
October1st to 15thDay
36%48%25%20%5%
1650
16th to endDay
33%310%29%18%3
1760
November1st to 15thDay
33%410%22%22%5%
1585
16th to endDay
43%310%27%13%1
1557
December1st to 15thDay
49%312%23%9%
1440
16th to endDay
49%413%20%10%2
1536
January1st to 15thNight
44%5%9%24%14%1
2473
16th to endNight
45%412%23%12%
2496
February1st to 15thNight
49%49%21%13%1
2259
16th to endNight
43%312%24%14%1
1893
March1st to 15thNight
49%38%23%12%2
2076
16th to endNight
50%6%12%21%9%
2046
April1st to 15thNight
38%5%9%24%18%3
1797
16th to endNight
38%49%28%16%2
1760
May1st to 15thNight
40%7%14%23%13%1
1519
16th to endNight
39%7%14%18%16%3
1370
June1st to 15thNight
29%6%14%28%17%2
1320
16th to endNight
27%5%16%25%20%5%
1320
July1st to 15thNight
31%6%11%31%14%4
1240
16th to endNight
25%5%16%32%17%1
1392
August1st to 15thNight
26%6%12%30%21%2
1519
16th to endNight
28%5%13%23%23%5%
1750
September1st to 15thNight
35%47%22%23%6%
1650
16th to endNight
31%5%8%25%25%4
1771
October1st to 15thNight
30%5%9%24%23%5%
1980
16th to endNight
35%38%26%20%5%
2112
November1st to 15thNight
31%411%23%21%7%
2273
16th to endNight
40%39%26%17%1
2402
December1st to 15thNight
51%410%21%11%
2520
16th to endNight
53%49%19%10%2
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
30%22%37%6%21
90
16th to endDay
13%30%41%13%1
96
February1st to 15thDay
14%28%37%15%3
90
16th to endDay
20%23%34%18%2
81
March1st to 15thDay
27%22%37%7%31
90
16th to endDay
19%21%36%18%3
161
April1st to 15thDay
17%13%35%21%11%
270
16th to endDay
17%12%36%20%11%1
254
May1st to 15thDay
18%16%32%20%9%3
286
16th to endDay
18%9%29%25%10%6%
437
June1st to 15thDay
11%328%31%18%6%
420
16th to endDay
8%326%37%20%4
420
July1st to 15thDay
13%321%31%23%7%
400
16th to endDay
6%217%32%33%7%
445
August1st to 15thDay
9%10%35%31%12%
374
16th to endDay
10%216%26%32%12%
268
September1st to 15thDay
14%413%30%28%9%
255
16th to endDay
11%6%17%25%25%13%
232
October1st to 15thDay
10%16%22%34%14%2
90
16th to endDay
13%12%37%28%8%
96
November1st to 15thDay
5%8%25%30%20%10%
90
16th to endDay
32%23%27%10%42
90
December1st to 15thDay
14%20%40%17%34
90
16th to endDay
26%25%39%8%1
96
January1st to 15thNight
19%19%34%21%4
900
16th to endNight
18%19%38%20%2
960
February1st to 15thNight
20%19%34%22%2
850
16th to endNight
19%17%41%19%1
631
March1st to 15thNight
25%12%37%19%4
636
16th to endNight
22%12%36%21%6%
576
April1st to 15thNight
16%16%37%21%7%
539
16th to endNight
16%9%36%29%7%
528
May1st to 15thNight
18%5%32%32%9%1
495
16th to endNight
13%5%29%33%17%1
515
June1st to 15thNight
9%323%42%20%1
495
16th to endNight
8%122%41%23%1
495
July1st to 15thNight
12%115%41%24%4
465
16th to endNight
414%38%37%3
522
August1st to 15thNight
5%18%40%39%4
494
16th to endNight
7%12%42%32%5%
525
September1st to 15thNight
14%314%33%28%6%
495
16th to endNight
10%5%18%29%28%6%
594
October1st to 15thNight
12%6%27%27%21%3
660
16th to endNight
18%11%36%25%7%
704
November1st to 15thNight
14%12%33%26%12%
700
16th to endNight
21%15%35%21%6%
782
December1st to 15thNight
26%15%31%20%5%
900
16th to endNight
25%15%35%22%1
960
Page generated at 2017-04-27 16:48:49. Version ac04

Copyright 2017 A. Danko


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