Little Eden Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little Eden Observatory clear sky chart from 2005-11-05 to 2017-03-21.

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
45%
15119
26%
45172
17%
15072
53%
15072
31%
26656

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
9%
895
43%
895
29%
1451
January16th to endNight
28%
960
30%
2496
9%
960
41%
960
31%
1541
February1st to 15thNight
25%
880
21%
2285
6%
875
34%
875
26%
1489
February16th to endNight
24%
570
27%
1832
9%
570
40%
570
26%
1065
March1st to 15thNight
29%
540
22%
1980
14%
540
39%
540
20%
1227
March16th to endNight
34%
546
18%
2002
16%
546
41%
546
22%
1231
April1st to 15thNight
30%
494
25%
1691
14%
494
46%
494
26%
953
April16th to endNight
32%
495
23%
1650
15%
495
47%
495
29%
954
May1st to 15thNight
41%
495
21%
1543
15%
495
51%
495
25%
976
May16th to endNight
49%
515
20%
1541
17%
513
56%
513
31%
940
June1st to 15thNight
68%
495
24%
1485
21%
495
73%
495
42%
802
June16th to endNight
72%
495
23%
1485
23%
495
76%
495
45%
779
July1st to 15thNight
75%
465
20%
1395
21%
465
78%
465
40%
781
July16th to endNight
80%
522
24%
1468
28%
489
81%
489
43%
794
August1st to 15thNight
80%
494
27%
1475
30%
491
81%
491
46%
767
August16th to endNight
75%
525
22%
1747
27%
525
75%
525
34%
973
September1st to 15thNight
66%
495
26%
1669
29%
495
69%
495
32%
957
September16th to endNight
67%
506
32%
1829
30%
506
73%
506
35%
952
October1st to 15thNight
54%
660
30%
1980
22%
660
59%
660
35%
1141
October16th to endNight
49%
704
35%
2112
21%
704
60%
704
42%
1112
November1st to 15thNight
44%
700
31%
2100
19%
700
55%
700
35%
1167
November16th to endNight
35%
804
30%
2244
15%
804
46%
804
29%
1400
December1st to 15thNight
34%
900
23%
2340
11%
900
42%
900
28%
1540
December16th to endNight
30%
960
25%
2496
10%
960
40%
960
26%
1664

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%25%5%3445%6%42%
45681
Night
11%5%24423347%50%
45370
TransparencyDay
40%5%10%21%17%4
45381
Night
33%410%22%21%6%
45175
SeeingDay
13%6%21%27%23%8%
4904
Night
14%9%25%28%19%2
15120

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
15%6%35%32333450%
1611
16th to endDay
16%6%23323235%50%
1728
February1st to 15thDay
17%6%245%23335%45%
1575
16th to endDay
17%8%46%423335%41%
1650
March1st to 15thDay
18%6%35%413335%43%
1980
16th to endDay
17%8%37%424345%37%
1989
April1st to 15thDay
15%6%34333345%45%
1927
16th to endDay
17%5%36%5%34345%40%
1980
May1st to 15thDay
18%6%37%5%34346%35%
2075
16th to endDay
12%7%36%7%36%6%5%7%34%
2222
June1st to 15thDay
7%426%6%46%5%6%9%40%
2145
16th to endDay
4435%7%5%6%6%5%8%42%
2145
July1st to 15thDay
8%6%25%6%5%6%7%7%10%31%
2145
16th to endDay
6%2247%48%6%8%11%36%
2284
August1st to 15thDay
5%2235%46%8%7%11%41%
2145
16th to endDay
9%425%6%47%6%7%9%36%
2103
September1st to 15thDay
16%5%145%345%7%6%38%
1958
16th to endDay
9%3145%3435%6%51%
1790
October1st to 15thDay
14%5%25%32434449%
1650
16th to endDay
13%313222235%58%
1760
November1st to 15thDay
11%423323337%53%
1758
16th to endDay
15%7%24323225%50%
1713
December1st to 15thDay
15%7%35%323345%45%
1620
16th to endDay
17%9%3442323444%
1728
January1st to 15thNight
14%6%23313335%52%
2327
16th to endNight
14%5%23223245%53%
2496
February1st to 15thNight
15%7%35%313335%48%
2278
16th to endNight
12%6%3332335%6%50%
1832
March1st to 15thNight
17%6%25%424345%43%
1980
16th to endNight
12%7%35%5%2435%6%43%
2002
April1st to 15thNight
10%424434347%51%
1691
16th to endNight
11%42442344452%
1650
May1st to 15thNight
12%424425%45%8%43%
1542
16th to endNight
7%6%36%42446%9%45%
1539
June1st to 15thNight
4223424348%58%
1485
16th to endNight
431222345%9%58%
1485
July1st to 15thNight
43133347%9%13%44%
1485
16th to endNight
421342446%11%54%
1576
August1st to 15thNight
321232446%11%54%
1485
16th to endNight
6%3245%245%8%10%46%
1747
September1st to 15thNight
11%42332446%7%50%
1669
16th to endNight
7%31442445%6%55%
1829
October1st to 15thNight
10%5%23323335%54%
1980
16th to endNight
11%312312235%62%
2112
November1st to 15thNight
9%5%13322345%57%
2100
16th to endNight
14%5%24323335%50%
2244
December1st to 15thNight
15%7%24323345%45%
2340
16th to endNight
17%6%35%423235%45%
2496

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
39%26%25%19%6%
1612
16th to endDay
38%27%22%23%4
1728
February1st to 15thDay
41%39%21%18%4
1576
16th to endDay
47%25%19%18%5%
1650
March1st to 15thDay
44%39%18%17%7%
1980
16th to endDay
50%47%20%15%1
1991
April1st to 15thDay
41%38%20%18%6%
1927
16th to endDay
45%48%18%20%2
1980
May1st to 15thDay
50%5%8%17%13%3
2075
16th to endDay
47%6%12%20%11%1
2226
June1st to 15thDay
38%7%13%23%15%1
2145
16th to endDay
38%6%12%24%16%1
2145
July1st to 15thDay
40%9%16%22%9%
2006
16th to endDay
37%10%16%22%13%
2129
August1st to 15thDay
30%11%13%25%17%1
2131
16th to endDay
39%8%14%20%12%3
2103
September1st to 15thDay
42%7%11%16%14%8%
1958
16th to endDay
31%5%9%22%22%8%
1790
October1st to 15thDay
37%48%18%22%9%
1650
16th to endDay
29%27%20%27%12%
1760
November1st to 15thDay
31%38%25%23%7%
1758
16th to endDay
38%3419%25%7%
1713
December1st to 15thDay
41%310%20%17%5%
1620
16th to endDay
45%27%20%19%4
1728
January1st to 15thNight
35%37%19%28%5%
2327
16th to endNight
34%37%22%25%6%
2496
February1st to 15thNight
39%37%22%19%6%
2288
16th to endNight
35%38%25%19%7%
1832
March1st to 15thNight
43%48%16%18%8%
1980
16th to endNight
41%49%19%20%3
2002
April1st to 15thNight
32%5%11%19%19%10%
1691
16th to endNight
33%5%9%22%24%4
1650
May1st to 15thNight
40%5%11%21%14%6%
1543
16th to endNight
34%6%17%26%12%1
1541
June1st to 15thNight
24%5%12%32%20%2
1485
16th to endNight
22%6%14%28%25%3
1485
July1st to 15thNight
24%9%21%27%15%2
1395
16th to endNight
22%8%16%33%18%1
1468
August1st to 15thNight
20%7%18%29%20%3
1475
16th to endNight
30%5%16%24%18%3
1747
September1st to 15thNight
32%6%11%21%19%8%
1669
16th to endNight
28%48%23%25%8%
1829
October1st to 15thNight
31%48%18%22%13%
1980
16th to endNight
26%26%20%30%14%
2112
November1st to 15thNight
30%37%23%24%11%
2100
16th to endNight
38%25%17%28%6%
2244
December1st to 15thNight
41%39%18%20%6%
2340
16th to endNight
43%27%21%18%7%
2496

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
22%15%35%21%5%
90
16th to endDay
25%25%31%13%41
96
February1st to 15thDay
21%20%42%12%31
90
16th to endDay
29%28%27%12%2
81
March1st to 15thDay
27%21%37%12%1
90
16th to endDay
12%23%33%28%1
63
April1st to 15thDay
21%16%34%17%9%1
166
16th to endDay
21%9%31%20%13%3
210
May1st to 15thDay
18%12%35%23%8%2
332
16th to endDay
13%332%28%15%5%
437
June1st to 15thDay
10%217%28%31%9%
420
16th to endDay
5%219%35%27%10%
420
July1st to 15thDay
8%219%34%27%7%
400
16th to endDay
45%30%41%17%
445
August1st to 15thDay
6%8%30%38%15%
418
16th to endDay
12%3425%38%15%
271
September1st to 15thDay
11%16%24%42%13%
233
16th to endDay
412%40%33%10%
90
October1st to 15thDay
6%330%45%11%3
90
16th to endDay
21%225%38%10%2
96
November1st to 15thDay
20%13%18%23%22%2
90
16th to endDay
32%17%27%16%32
90
December1st to 15thDay
17%14%41%17%5%3
90
16th to endDay
22%19%40%11%41
96
January1st to 15thNight
20%17%29%26%6%
900
16th to endNight
18%16%35%25%4
960
February1st to 15thNight
20%17%32%25%4
880
16th to endNight
17%17%38%21%5%
570
March1st to 15thNight
22%10%31%29%5%
540
16th to endNight
16%12%30%31%8%1
546
April1st to 15thNight
11%17%37%23%9%
494
16th to endNight
15%10%37%24%11%
495
May1st to 15thNight
14%6%31%33%12%
495
16th to endNight
10%427%31%23%2
515
June1st to 15thNight
5%215%37%36%2
495
16th to endNight
4214%32%38%6%
495
July1st to 15thNight
419%38%42%4
465
16th to endNight
4331%48%11%
522
August1st to 15thNight
5%16%32%44%9%
494
16th to endNight
7%15%29%49%6%
525
September1st to 15thNight
13%110%24%44%4
495
16th to endNight
9%113%31%37%6%
506
October1st to 15thNight
13%5%21%28%27%3
660
16th to endNight
13%7%27%30%18%2
704
November1st to 15thNight
12%11%27%32%15%1
700
16th to endNight
19%13%28%26%11%
804
December1st to 15thNight
20%11%29%29%7%
900
16th to endNight
22%12%29%27%6%
960
Page generated at 2017-03-22 01:42:23. Version ac04

Copyright 2017 A. Danko


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