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 2017-12-01.

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
46%
15949
26%
47766
17%
15902
54%
15902
32%
27978

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%
576
19%
2112
17%
576
42%
576
23%
1287
April1st to 15thNight
31%
539
24%
1845
14%
539
47%
539
27%
1035
April16th to endNight
33%
540
24%
1800
16%
540
49%
540
29%
1035
May1st to 15thNight
43%
540
20%
1683
15%
540
53%
540
26%
1037
May16th to endNight
49%
563
22%
1685
17%
561
57%
561
33%
1009
June1st to 15thNight
69%
540
22%
1620
20%
540
73%
540
42%
875
June16th to endNight
72%
540
25%
1620
24%
540
76%
540
45%
853
July1st to 15thNight
76%
510
18%
1530
20%
510
78%
510
40%
852
July16th to endNight
80%
564
25%
1594
30%
531
81%
531
43%
859
August1st to 15thNight
79%
539
25%
1610
28%
536
80%
536
44%
847
August16th to endNight
74%
573
23%
1907
28%
573
75%
573
34%
1074
September1st to 15thNight
68%
540
26%
1821
28%
540
71%
540
34%
1016
September16th to endNight
68%
552
34%
1995
33%
552
73%
552
36%
1029
October1st to 15thNight
54%
720
29%
2160
21%
720
60%
720
36%
1239
October16th to endNight
48%
768
37%
2304
23%
768
61%
768
44%
1190
November1st to 15thNight
43%
760
29%
2280
18%
760
53%
760
34%
1278
November16th to endNight
37%
871
32%
2431
17%
871
49%
871
31%
1480
December1st to 15thNight
34%
905
23%
2353
11%
905
42%
905
28%
1546
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
12%5%25%5%3445%6%43%
48655
Night
10%5%24423347%51%
47964
TransparencyDay
40%5%10%21%17%4
48355
Night
33%410%23%21%6%
47769
SeeingDay
12%6%22%27%22%7%
5923
Night
14%9%24%29%19%2
15950

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
16%8%37%424345%37%
2110
April1st to 15thDay
15%6%34432346%45%
2103
16th to endDay
17%5%36%5%34445%39%
2160
May1st to 15thDay
17%6%36%5%34346%37%
2265
16th to endDay
11%6%36%7%36%6%5%7%35%
2430
June1st to 15thDay
7%5%25%6%46%5%6%9%40%
2340
16th to endDay
4436%7%5%6%6%5%8%41%
2340
July1st to 15thDay
8%6%25%6%5%6%7%8%10%31%
2340
16th to endDay
6%2247%47%6%8%10%37%
2466
August1st to 15thDay
7%3246%46%7%7%10%39%
2340
16th to endDay
9%5%26%6%47%7%7%9%35%
2295
September1st to 15thDay
15%5%145%3446%6%41%
2136
16th to endDay
9%3135%3445%6%51%
1953
October1st to 15thDay
13%425%324345%49%
1800
16th to endDay
13%31322223459%
1920
November1st to 15thDay
11%5%23423337%51%
1908
16th to endDay
14%7%24323225%51%
1856
December1st to 15thDay
15%7%34323345%45%
1621
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%44%
2112
April1st to 15thNight
10%414424347%51%
1845
16th to endNight
11%424413445%52%
1800
May1st to 15thNight
12%424425%35%7%46%
1682
16th to endNight
6%5%35%42447%9%46%
1683
June1st to 15thNight
4223424348%58%
1620
16th to endNight
5%31222345%9%58%
1620
July1st to 15thNight
4313335%7%9%13%45%
1620
16th to endNight
321342446%11%54%
1702
August1st to 15thNight
32124345%6%11%53%
1620
16th to endNight
6%3245%246%8%10%45%
1907
September1st to 15thNight
10%42332445%7%52%
1821
16th to endNight
7%31442435%6%56%
1995
October1st to 15thNight
10%5%23323335%55%
2160
16th to endNight
10%312312235%64%
2304
November1st to 15thNight
9%5%13323346%56%
2280
16th to endNight
13%5%24323335%52%
2431
December1st to 15thNight
15%7%24323345%46%
2353
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
49%48%20%14%1
2112
April1st to 15thDay
41%39%21%18%5%
2103
16th to endDay
45%5%8%18%18%3
2160
May1st to 15thDay
48%5%8%17%16%3
2265
16th to endDay
46%5%12%21%12%1
2434
June1st to 15thDay
38%7%12%24%16%1
2340
16th to endDay
38%6%12%23%16%1
2340
July1st to 15thDay
39%9%16%23%9%
2201
16th to endDay
36%9%15%23%14%
2311
August1st to 15thDay
34%10%13%24%15%1
2326
16th to endDay
40%8%14%20%12%3
2295
September1st to 15thDay
40%6%11%19%14%8%
2136
16th to endDay
30%5%9%24%21%7%
1953
October1st to 15thDay
36%49%18%22%9%
1800
16th to endDay
29%27%19%27%13%
1920
November1st to 15thDay
33%48%25%22%6%
1908
16th to endDay
37%35%19%26%7%
1856
December1st to 15thDay
41%310%20%17%5%
1621
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
40%410%20%19%3
2112
April1st to 15thNight
32%5%11%20%19%10%
1845
16th to endNight
33%5%9%23%24%4
1800
May1st to 15thNight
38%5%11%20%17%6%
1683
16th to endNight
32%6%18%26%13%1
1685
June1st to 15thNight
24%6%12%32%21%2
1620
16th to endNight
22%5%13%28%26%3
1620
July1st to 15thNight
23%9%20%28%15%2
1530
16th to endNight
22%8%15%34%18%1
1594
August1st to 15thNight
21%7%19%29%19%3
1610
16th to endNight
31%5%16%25%17%3
1907
September1st to 15thNight
30%6%10%22%21%8%
1821
16th to endNight
27%48%24%25%8%
1995
October1st to 15thNight
31%49%20%21%13%
2160
16th to endNight
25%26%20%31%14%
2304
November1st to 15thNight
30%38%22%23%10%
2280
16th to endNight
35%26%18%29%7%
2431
December1st to 15thNight
40%39%18%20%6%
2353
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
13%21%36%26%2
96
April1st to 15thDay
20%16%33%18%9%1
222
16th to endDay
20%11%32%20%11%2
270
May1st to 15thDay
16%11%34%24%10%2
402
16th to endDay
13%5%35%26%14%4
517
June1st to 15thDay
11%215%32%28%9%
495
16th to endDay
5%222%35%25%8%
495
July1st to 15thDay
7%218%34%29%8%
475
16th to endDay
4431%41%18%
515
August1st to 15thDay
9%8%32%35%13%
493
16th to endDay
11%25%27%37%14%
335
September1st to 15thDay
9%17%26%41%12%
291
16th to endDay
5%11%46%28%8%
135
October1st to 15thDay
6%5%26%41%16%2
135
16th to endDay
18%6%31%31%10%2
144
November1st to 15thDay
20%14%22%24%17%1
135
16th to endDay
24%14%32%20%5%2
135
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
15%12%30%31%8%1
576
April1st to 15thNight
11%17%35%24%10%
539
16th to endNight
14%10%36%25%12%
540
May1st to 15thNight
14%6%30%33%13%1
540
16th to endNight
9%429%32%22%2
563
June1st to 15thNight
5%214%38%36%3
540
16th to endNight
5%214%33%38%6%
540
July1st to 15thNight
49%36%43%5%
510
16th to endNight
4330%48%12%
564
August1st to 15thNight
5%6%32%45%9%
539
16th to endNight
8%15%29%48%6%
573
September1st to 15thNight
12%110%25%46%4
540
16th to endNight
9%112%31%38%6%
552
October1st to 15thNight
12%5%21%28%27%3
720
16th to endNight
12%7%28%30%18%2
768
November1st to 15thNight
12%10%27%32%15%1
760
16th to endNight
18%12%27%28%12%
871
December1st to 15thNight
20%11%29%29%7%
905
16th to endNight
22%12%29%27%6%
960
Page generated at 2017-12-02 08:14:27. Version ac04

Copyright 2017 A. Danko


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