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 2017-12-20.

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
38%
16244
22%
48065
13%
16197
46%
16197
27%
30269

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%
540
22%
1800
14%
540
47%
540
26%
1097
May1st to 15thNight
38%
540
18%
1655
11%
539
47%
539
25%
1060
May16th to endNight
46%
563
20%
1497
12%
561
51%
561
30%
979
June1st to 15thNight
60%
540
20%
1440
14%
540
64%
540
41%
853
June16th to endNight
59%
540
22%
1440
14%
540
64%
540
43%
838
July1st to 15thNight
64%
510
19%
1360
15%
510
66%
510
39%
822
July16th to endNight
70%
564
23%
1513
21%
531
72%
531
43%
841
August1st to 15thNight
73%
539
23%
1658
26%
536
75%
536
38%
928
August16th to endNight
73%
573
23%
1910
26%
573
76%
573
37%
1023
September1st to 15thNight
62%
540
26%
1800
27%
540
66%
540
30%
1032
September16th to endNight
61%
649
33%
1933
25%
649
67%
649
36%
1099
October1st to 15thNight
48%
720
28%
2160
19%
720
55%
720
33%
1259
October16th to endNight
31%
768
28%
2304
15%
768
43%
768
31%
1351
November1st to 15thNight
35%
760
26%
2468
15%
760
49%
760
29%
1408
November16th to endNight
27%
847
24%
2602
12%
847
40%
847
26%
1597
December1st to 15thNight
24%
975
17%
2730
6%
975
34%
975
20%
1916
December16th to endNight
19%
984
17%
2755
6%
984
29%
984
17%
2019

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%
48777
Night
12%6%24423446%45%
48249
TransparencyDay
40%6%11%23%15%2
48465
Night
39%5%10%24%17%3
48067
SeeingDay
13%9%25%26%18%5%
6170
Night
16%10%30%27%13%1
16244

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
17%6%36%6%3445%5%36%
2160
May1st to 15thDay
18%5%25%42445%8%36%
2292
16th to endDay
12%425%5%345%5%8%41%
2617
June1st to 15thDay
8%4245%35%5%6%8%46%
2520
16th to endDay
6%323425%6%7%12%45%
2520
July1st to 15thDay
9%4134345%7%10%44%
2520
16th to endDay
6%224435%6%6%10%47%
2548
August1st to 15thDay
8%325%5%36%6%5%10%42%
2292
16th to endDay
8%4245%345%6%9%43%
2292
September1st to 15thDay
13%41442345%7%46%
2160
16th to endDay
9%415%423447%50%
2011
October1st to 15thDay
15%5%25%423335%49%
1800
16th to endDay
12%5%1332334454%
1920
November1st to 15thDay
13%5%23423336%51%
1720
16th to endDay
15%7%24424246%43%
1687
December1st to 15thDay
15%10%26%433436%39%
1560
16th to endDay
16%11%36%423446%36%
1568
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
16%5%245%2335%6%44%
1800
May1st to 15thNight
16%5%2442235%7%44%
1655
16th to endNight
10%5%345%345%48%45%
1496
June1st to 15thNight
6%31343445%8%53%
1440
16th to endNight
7%21332446%11%52%
1440
July1st to 15thNight
9%41342435%7%52%
1440
16th to endNight
331443446%11%51%
1617
August1st to 15thNight
5%223435%45%8%53%
1668
16th to endNight
5%2135%3445%9%53%
1910
September1st to 15thNight
12%425%33335%6%50%
1800
16th to endNight
7%424423447%54%
1933
October1st to 15thNight
11%424333445%53%
2160
16th to endNight
13%6%13322335%52%
2304
November1st to 15thNight
11%5%24322347%52%
2468
16th to endNight
15%6%34313345%47%
2602
December1st to 15thNight
18%9%35%5%23346%35%
2730
16th to endNight
18%11%46%5%2434434%
2755

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%5%10%21%12%1
2160
May1st to 15thDay
45%7%12%22%10%
2292
16th to endDay
41%8%13%19%14%3
2621
June1st to 15thDay
34%8%12%25%17%1
2520
16th to endDay
28%8%16%25%17%3
2520
July1st to 15thDay
33%8%13%27%13%4
2371
16th to endDay
30%7%15%28%15%1
2390
August1st to 15thDay
34%8%12%25%17%1
2278
16th to endDay
34%7%12%21%18%5%
2292
September1st to 15thDay
35%6%9%23%20%4
2160
16th to endDay
32%5%8%29%20%2
2011
October1st to 15thDay
38%49%24%18%5%
1800
16th to endDay
33%310%29%19%3
1920
November1st to 15thDay
35%410%23%21%5%
1720
16th to endDay
42%39%28%14%1
1687
December1st to 15thDay
47%412%24%10%
1560
16th to endDay
49%413%19%10%2
1568
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
40%49%28%15%2
1800
May1st to 15thNight
39%6%13%23%15%1
1656
16th to endNight
37%7%14%20%16%3
1498
June1st to 15thNight
27%6%14%28%20%2
1440
16th to endNight
26%5%15%25%21%5%
1440
July1st to 15thNight
30%5%11%32%14%5%
1360
16th to endNight
25%5%15%32%18%1
1513
August1st to 15thNight
27%7%11%29%21%2
1658
16th to endNight
27%5%13%23%24%5%
1910
September1st to 15thNight
34%47%22%22%6%
1800
16th to endNight
30%5%8%26%25%3
1933
October1st to 15thNight
32%5%9%24%23%5%
2160
16th to endNight
34%38%26%21%4
2304
November1st to 15thNight
33%410%23%20%7%
2468
16th to endNight
39%39%27%18%1
2602
December1st to 15thNight
49%410%22%12%1
2730
16th to endNight
53%49%19%10%2
2755

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
19%13%35%20%10%1
270
May1st to 15thDay
18%16%31%20%9%3
351
16th to endDay
17%9%31%26%9%5%
517
June1st to 15thDay
9%326%33%20%6%
495
16th to endDay
7%5%29%35%18%3
495
July1st to 15thDay
13%220%31%24%6%
475
16th to endDay
6%117%32%34%7%
515
August1st to 15thDay
11%19%35%30%11%
445
16th to endDay
9%217%29%31%10%
332
September1st to 15thDay
13%5%13%29%28%10%
315
16th to endDay
9%5%16%26%29%12%
290
October1st to 15thDay
17%16%19%34%11%1
135
16th to endDay
13%15%36%25%9%
144
November1st to 15thDay
14%7%28%27%14%6%
135
16th to endDay
23%20%31%19%41
135
December1st to 15thDay
10%28%35%17%5%3
135
16th to endDay
24%24%42%8%
108
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
17%9%36%29%7%
540
May1st to 15thNight
17%5%32%31%10%1
540
16th to endNight
12%430%34%16%1
563
June1st to 15thNight
8%222%42%21%1
540
16th to endNight
8%124%42%21%1
540
July1st to 15thNight
11%115%42%25%3
510
16th to endNight
415%38%37%3
564
August1st to 15thNight
6%10%39%38%4
539
16th to endNight
6%12%41%33%4
573
September1st to 15thNight
14%314%32%28%6%
540
16th to endNight
10%418%31%28%6%
649
October1st to 15thNight
13%6%27%28%20%3
720
16th to endNight
18%11%37%24%7%
768
November1st to 15thNight
15%12%33%25%11%
760
16th to endNight
19%15%36%21%7%
847
December1st to 15thNight
24%16%30%21%5%
975
16th to endNight
25%14%36%22%1
984
Page generated at 2017-12-21 06:04:55. Version ac04

Copyright 2017 A. Danko


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