Bonny Doon Airfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bonny Doon Airfield clear sky chart from 2005-11-05 to 2017-08-12.

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
66%
15320
25%
46555
23%
15284
70%
15284
36%
26387

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
59%
716
20%
2360
20%
716
63%
716
32%
1348
January16th to endNight
61%
768
25%
2496
26%
768
64%
768
30%
1475
February1st to 15thNight
56%
698
23%
2284
23%
698
61%
698
27%
1405
February16th to endNight
52%
632
22%
1895
19%
632
58%
632
29%
1190
March1st to 15thNight
56%
720
19%
1998
17%
720
59%
720
29%
1287
March16th to endNight
54%
768
21%
2091
15%
768
59%
768
32%
1323
April1st to 15thNight
51%
719
22%
1799
13%
719
55%
719
34%
1161
April16th to endNight
58%
720
25%
1800
11%
720
63%
720
43%
1054
May1st to 15thNight
69%
629
23%
1709
16%
629
70%
629
45%
942
May16th to endNight
68%
417
22%
1540
19%
417
74%
417
33%
793
June1st to 15thNight
73%
360
24%
1440
26%
360
79%
360
33%
727
June16th to endNight
90%
360
31%
1440
40%
360
91%
360
47%
604
July1st to 15thNight
87%
410
26%
1430
30%
410
87%
410
44%
666
July16th to endNight
80%
564
27%
1593
25%
531
80%
531
33%
922
August1st to 15thNight
76%
551
25%
1600
20%
548
76%
548
32%
959
August16th to endNight
82%
700
28%
1750
18%
700
82%
700
46%
1034
September1st to 15thNight
87%
660
35%
1650
26%
660
87%
660
56%
898
September16th to endNight
82%
656
38%
1799
36%
656
84%
656
58%
888
October1st to 15thNight
73%
660
29%
1980
31%
660
76%
660
44%
1040
October16th to endNight
72%
704
32%
2112
34%
704
76%
704
41%
1141
November1st to 15thNight
70%
700
30%
2166
30%
700
73%
700
43%
1129
November16th to endNight
66%
720
26%
2415
27%
720
69%
720
35%
1296
December1st to 15thNight
56%
720
23%
2520
20%
720
63%
720
27%
1503
December16th to endNight
49%
768
21%
2688
19%
768
56%
768
26%
1602

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
9%423323347%55%
47409
Night
9%41332345%7%53%
46745
TransparencyDay
29%39%20%23%13%
47099
Night
31%49%19%21%14%
46556
SeeingDay
10%5%19%34%24%6%
5916
Night
11%210%29%34%10%
15332

By Month

Percentage Cloud Cover SW (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
16%325%423447%46%
1576
16th to endDay
17%6%24423346%45%
1728
February1st to 15thDay
20%5%2332335%6%42%
1579
16th to endDay
21%7%25%324336%38%
1579
March1st to 15thDay
17%5%35%4345%5%9%35%
1959
16th to endDay
15%5%345%35%437%41%
2131
April1st to 15thDay
16%6%25%224447%43%
2149
16th to endDay
8%414323348%55%
2160
May1st to 15thDay
6%412213348%60%
2238
16th to endDay
7%6%34424347%53%
2569
June1st to 15thDay
5%42332345%8%56%
2520
16th to endDay
1112212237%73%
2520
July1st to 15thDay
1212413249%65%
2441
16th to endDay
12122122410%67%
2468
August1st to 15thDay
13133113410%64%
2266
16th to endDay
2133122410%66%
2100
September1st to 15thDay
222212239%70%
1980
16th to endDay
4212212335%70%
1827
October1st to 15thDay
6%323312436%60%
1650
16th to endDay
8%413323336%58%
1760
November1st to 15thDay
9%3343235%46%53%
1691
16th to endDay
15%5%23322346%50%
1542
December1st to 15thDay
19%6%2432435%6%40%
1440
16th to endDay
20%6%2432235%7%40%
1536
January1st to 15thNight
14%414324447%46%
2360
16th to endNight
17%413323347%47%
2496
February1st to 15thNight
17%5%2441445%7%42%
2272
16th to endNight
17%6%2441346%7%41%
1895
March1st to 15thNight
17%5%2432345%5%43%
1998
16th to endNight
14%5%2432445%7%45%
2091
April1st to 15thNight
14%5%144235%5%7%45%
1799
16th to endNight
8%31331335%7%57%
1800
May1st to 15thNight
34143132411%58%
1709
16th to endNight
432432345%10%55%
1539
June1st to 15thNight
22134235%7%9%57%
1440
16th to endNight
21122325%8%70%
1440
July1st to 15thNight
21332345%9%63%
1516
16th to endNight
125%5%245%6%11%53%
1701
August1st to 15thNight
317%6%3336%11%52%
1609
16th to endNight
325%433448%59%
1750
September1st to 15thNight
1112223438%65%
1650
16th to endNight
3213212238%69%
1799
October1st to 15thNight
6%413313346%61%
1980
16th to endNight
6%314313245%60%
2112
November1st to 15thNight
9%412313347%58%
2166
16th to endNight
8%424323347%53%
2415
December1st to 15thNight
18%5%24314346%45%
2520
16th to endNight
19%5%2331445%6%44%
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
35%413%19%15%10%
1576
16th to endDay
39%49%12%20%13%
1728
February1st to 15thDay
41%29%19%20%6%
1579
16th to endDay
46%48%24%12%4
1579
March1st to 15thDay
41%5%11%21%14%5%
1959
16th to endDay
41%6%13%19%15%3
2131
April1st to 15thDay
37%5%14%20%20%2
2149
16th to endDay
28%413%26%19%7%
2160
May1st to 15thDay
23%312%28%25%6%
2238
16th to endDay
31%413%24%20%5%
2573
June1st to 15thDay
26%5%12%23%21%9%
2520
16th to endDay
16%36%20%33%20%
2520
July1st to 15thDay
21%2312%28%31%
2298
16th to endDay
19%3315%31%27%
2313
August1st to 15thDay
22%2316%29%25%
2250
16th to endDay
20%2421%28%22%
2100
September1st to 15thDay
17%25%17%29%27%
1980
16th to endDay
18%25%24%29%19%
1827
October1st to 15thDay
23%39%21%24%16%
1650
16th to endDay
28%210%24%21%13%
1760
November1st to 15thDay
30%310%29%20%6%
1691
16th to endDay
35%211%19%25%6%
1542
December1st to 15thDay
42%411%17%18%6%
1440
16th to endDay
41%314%15%18%6%
1536
January1st to 15thNight
34%312%22%17%9%
2360
16th to endNight
36%411%13%17%16%
2496
February1st to 15thNight
40%49%19%18%9%
2284
16th to endNight
39%413%26%13%3
1895
March1st to 15thNight
40%412%20%16%7%
1998
16th to endNight
37%413%20%18%5%
2091
April1st to 15thNight
36%414%23%17%3
1799
16th to endNight
25%5%12%27%20%8%
1800
May1st to 15thNight
26%311%20%27%11%
1710
16th to endNight
26%6%15%22%22%5%
1540
June1st to 15thNight
25%7%9%21%21%14%
1440
16th to endNight
17%45%14%31%26%
1440
July1st to 15thNight
20%5%211%22%37%
1430
16th to endNight
31%6%411%19%26%
1593
August1st to 15thNight
35%5%112%22%22%
1600
16th to endNight
27%3213%25%27%
1750
September1st to 15thNight
20%2413%26%32%
1650
16th to endNight
17%2321%35%19%
1799
October1st to 15thNight
24%39%21%22%18%
1980
16th to endNight
27%36%23%22%16%
2112
November1st to 15thNight
26%312%26%24%8%
2166
16th to endNight
29%39%22%22%10%
2415
December1st to 15thNight
39%310%18%20%8%
2520
16th to endNight
39%314%16%17%7%
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
23%5%19%28%18%5%
205
16th to endDay
20%322%25%21%6%
256
February1st to 15thDay
21%6%21%24%21%5%
237
16th to endDay
21%8%23%28%14%3
238
March1st to 15thDay
21%6%27%22%18%4
270
16th to endDay
15%10%25%32%13%2
288
April1st to 15thDay
16%13%28%28%10%2
269
16th to endDay
6%14%32%27%15%2
270
May1st to 15thDay
9%9%30%33%14%2
288
16th to endDay
8%9%19%33%23%5%
330
June1st to 15thDay
6%5%27%39%18%2
315
16th to endDay
1116%43%31%6%
315
July1st to 15thDay
38%40%38%7%
305
16th to endDay
16%44%37%10%
327
August1st to 15thDay
311%43%35%6%
300
16th to endDay
29%43%35%8%
268
September1st to 15thDay
310%40%34%9%
255
16th to endDay
6%413%29%36%9%
255
October1st to 15thDay
6%418%38%24%7%
255
16th to endDay
11%420%32%25%5%
272
November1st to 15thDay
9%315%25%30%14%
197
16th to endDay
11%6%14%41%24%1
77
December1st to 15thDay
28%10%21%25%15%
60
16th to endDay
12%15%9%23%31%7%
64
January1st to 15thNight
17%211%28%30%9%
720
16th to endNight
18%29%30%28%10%
768
February1st to 15thNight
19%410%28%30%6%
704
16th to endNight
21%316%32%20%6%
632
March1st to 15thNight
19%412%26%30%6%
720
16th to endNight
17%315%32%26%4
768
April1st to 15thNight
16%5%17%33%24%3
719
16th to endNight
9%6%19%30%26%7%
720
May1st to 15thNight
7%213%34%34%7%
630
16th to endNight
6%413%32%33%9%
418
June1st to 15thNight
414%37%37%5%
360
16th to endNight
2436%48%7%
360
July1st to 15thNight
4122%55%16%
410
16th to endNight
31320%50%21%
564
August1st to 15thNight
5%6%25%48%13%
551
16th to endNight
5%324%52%13%
700
September1st to 15thNight
3324%50%18%
660
16th to endNight
415%26%44%17%
656
October1st to 15thNight
9%27%28%37%15%
660
16th to endNight
8%17%27%35%18%
704
November1st to 15thNight
11%10%29%36%11%
700
16th to endNight
9%310%33%32%10%
720
December1st to 15thNight
20%211%31%26%7%
720
16th to endNight
21%416%32%20%4
768
Page generated at 2017-08-13 11:16:33. Version ac04

Copyright 2017 A. Danko


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