Peaceful Meadow Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Peaceful Meadow Observatory clear sky chart from 2005-11-05 to 2017-09-24.

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
48%
15622
27%
46944
18%
15577
56%
15577
33%
27254

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
31%
898
28%
2327
10%
895
43%
895
29%
1476
January16th to endNight
29%
960
28%
2496
10%
960
40%
960
30%
1594
February1st to 15thNight
28%
880
23%
2288
6%
876
38%
876
30%
1446
February16th to endNight
28%
549
28%
1811
13%
549
43%
549
28%
1043
March1st to 15thNight
29%
540
25%
1980
14%
540
43%
540
23%
1177
March16th to endNight
33%
576
22%
2112
15%
576
44%
576
25%
1238
April1st to 15thNight
33%
539
26%
1840
16%
539
48%
539
32%
1008
April16th to endNight
38%
540
25%
1800
18%
540
52%
540
31%
1005
May1st to 15thNight
42%
540
22%
1722
16%
540
53%
540
29%
1037
May16th to endNight
53%
563
23%
1685
20%
561
60%
561
33%
1003
June1st to 15thNight
76%
540
24%
1620
23%
540
80%
540
44%
859
June16th to endNight
77%
540
25%
1620
26%
540
79%
540
45%
860
July1st to 15thNight
74%
510
20%
1530
22%
510
76%
510
40%
849
July16th to endNight
81%
564
26%
1594
32%
531
82%
531
45%
842
August1st to 15thNight
80%
539
27%
1631
31%
536
81%
536
50%
808
August16th to endNight
75%
573
23%
1910
29%
573
76%
573
32%
1098
September1st to 15thNight
70%
540
24%
1808
26%
540
72%
540
34%
1017
September16th to endNight
72%
539
35%
1934
35%
539
76%
539
40%
963
October1st to 15thNight
62%
660
32%
1980
25%
660
67%
660
39%
1099
October16th to endNight
54%
704
36%
2112
23%
704
64%
704
42%
1109
November1st to 15thNight
49%
700
29%
2100
19%
700
57%
700
35%
1187
November16th to endNight
38%
768
32%
2208
19%
768
50%
768
31%
1347
December1st to 15thNight
36%
900
24%
2340
12%
900
43%
900
29%
1535
December16th to endNight
32%
960
24%
2496
10%
960
41%
960
27%
1654

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%7%43%
47979
Night
11%424323347%51%
47139
TransparencyDay
39%410%21%19%5%
47679
Night
33%39%22%22%7%
46944
SeeingDay
12%5%19%27%27%8%
5672
Night
14%7%24%30%20%2
15624

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
17%7%23414235%47%
1611
16th to endDay
21%6%2432223446%
1728
February1st to 15thDay
18%6%24324435%44%
1575
16th to endDay
20%7%35%41223442%
1671
March1st to 15thDay
20%6%24323346%42%
1980
16th to endDay
15%8%36%5%33446%39%
2110
April1st to 15thDay
13%5%245%24446%46%
2106
16th to endDay
13%6%35%434446%42%
2160
May1st to 15thDay
16%7%35%6%34447%36%
2227
16th to endDay
8%7%36%6%36%6%6%9%36%
2430
June1st to 15thDay
6%426%6%46%6%7%8%40%
2340
16th to endDay
5%425%6%46%5%7%8%42%
2340
July1st to 15thDay
8%436%6%46%6%7%11%34%
2340
16th to endDay
7%3246%46%7%7%12%37%
2466
August1st to 15thDay
5%3145%36%6%8%9%44%
2318
16th to endDay
9%5%25%5%47%7%9%8%35%
2292
September1st to 15thDay
12%5%25%435%5%5%7%42%
2149
16th to endDay
9%3244245%5%7%51%
1871
October1st to 15thDay
13%6%25%42325%449%
1650
16th to endDay
13%41221123460%
1760
November1st to 15thDay
12%424213346%53%
1758
16th to endDay
17%6%2432323449%
1749
December1st to 15thDay
18%6%35%32334445%
1620
16th to endDay
20%7%35%31333443%
1728
January1st to 15thNight
17%6%13312235%51%
2327
16th to endNight
17%5%2331333450%
2496
February1st to 15thNight
16%6%23323335%49%
2278
16th to endNight
15%5%2422235%5%50%
1811
March1st to 15thNight
16%7%24423236%45%
1980
16th to endNight
14%6%34322336%46%
2112
April1st to 15thNight
10%43341335%7%52%
1840
16th to endNight
10%5%24423346%52%
1800
May1st to 15thNight
13%414424447%46%
1721
16th to endNight
8%434435%45%10%45%
1683
June1st to 15thNight
322432445%8%57%
1620
16th to endNight
5%31332445%9%57%
1620
July1st to 15thNight
5%2144245%7%13%46%
1620
16th to endNight
32135%245%6%11%53%
1702
August1st to 15thNight
321332437%11%56%
1641
16th to endNight
8%423335%6%7%10%44%
1910
September1st to 15thNight
8%42343445%8%51%
1808
16th to endNight
6%41331435%7%58%
1934
October1st to 15thNight
9%413323345%56%
1980
16th to endNight
12%312212235%62%
2112
November1st to 15thNight
9%324424346%55%
2100
16th to endNight
17%5%2432332352%
2208
December1st to 15thNight
18%6%24323345%45%
2340
16th to endNight
18%7%35%322335%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
41%25%21%22%7%
1612
16th to endDay
43%1321%25%4
1728
February1st to 15thDay
43%15%22%20%5%
1576
16th to endDay
46%25%18%20%6%
1671
March1st to 15thDay
43%38%20%19%5%
1980
16th to endDay
45%39%21%18%2
2112
April1st to 15thDay
38%39%22%18%7%
2106
16th to endDay
40%39%23%19%3
2160
May1st to 15thDay
47%49%17%17%4
2227
16th to endDay
42%5%14%23%12%1
2434
June1st to 15thDay
37%6%11%27%15%1
2340
16th to endDay
36%5%10%25%18%2
2340
July1st to 15thDay
37%7%16%24%13%
2201
16th to endDay
35%7%17%25%12%1
2311
August1st to 15thDay
32%7%14%27%16%1
2304
16th to endDay
40%8%15%21%12%2
2292
September1st to 15thDay
38%6%11%16%18%7%
2149
16th to endDay
31%48%24%22%8%
1871
October1st to 15thDay
37%37%16%22%13%
1650
16th to endDay
28%25%19%29%13%
1760
November1st to 15thDay
31%27%23%26%8%
1758
16th to endDay
40%1416%28%7%
1749
December1st to 15thDay
43%29%19%18%6%
1620
16th to endDay
44%27%20%19%4
1728
January1st to 15thNight
38%25%18%29%6%
2327
16th to endNight
39%25%17%26%8%
2496
February1st to 15thNight
38%16%23%21%7%
2288
16th to endNight
36%28%23%20%9%
1811
March1st to 15thNight
41%28%19%19%9%
1980
16th to endNight
39%310%20%22%4
2112
April1st to 15thNight
32%210%22%19%11%
1840
16th to endNight
33%39%24%23%5%
1800
May1st to 15thNight
37%48%22%19%8%
1722
16th to endNight
33%5%15%26%16%1
1685
June1st to 15thNight
23%5%11%33%22%3
1620
16th to endNight
23%5%13%26%26%4
1620
July1st to 15thNight
26%6%19%27%18%1
1530
16th to endNight
23%5%18%32%18%2
1594
August1st to 15thNight
21%319%32%20%3
1631
16th to endNight
31%6%15%23%18%3
1910
September1st to 15thNight
30%6%11%19%22%9%
1808
16th to endNight
25%47%24%25%11%
1934
October1st to 15thNight
30%28%18%23%16%
1980
16th to endNight
26%2419%29%18%
2112
November1st to 15thNight
31%37%19%26%11%
2100
16th to endNight
38%1416%30%9%
2208
December1st to 15thNight
41%29%19%19%7%
2340
16th to endNight
41%28%21%19%6%
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
17%14%36%25%41
90
16th to endDay
19%27%33%11%8%
96
February1st to 15thDay
22%13%47%11%5%
90
16th to endDay
20%22%39%14%2
81
March1st to 15thDay
34%17%32%13%2
90
16th to endDay
12%19%31%29%7%
96
April1st to 15thDay
16%14%34%20%11%1
225
16th to endDay
18%8%31%23%14%3
270
May1st to 15thDay
16%9%34%23%12%3
364
16th to endDay
11%5%28%31%17%4
517
June1st to 15thDay
8%12%34%33%10%
495
16th to endDay
5%214%36%31%9%
495
July1st to 15thDay
6%212%33%35%8%
475
16th to endDay
6%427%44%17%
515
August1st to 15thDay
9%7%26%41%14%
471
16th to endDay
16%1420%40%16%
332
September1st to 15thDay
9%6%22%46%14%
304
16th to endDay
211%29%43%11%
114
October1st to 15thDay
4127%37%25%3
90
16th to endDay
19%420%31%19%4
96
November1st to 15thDay
16%10%24%28%14%5%
90
16th to endDay
30%12%27%16%10%3
90
December1st to 15thDay
18%13%42%11%10%4
90
16th to endDay
27%19%36%13%12
96
January1st to 15thNight
22%14%27%27%7%
900
16th to endNight
20%11%35%27%4
960
February1st to 15thNight
21%13%33%26%5%
880
16th to endNight
18%14%36%25%5%
549
March1st to 15thNight
20%9%37%26%5%
540
16th to endNight
17%10%34%28%8%
576
April1st to 15thNight
12%13%37%26%10%
539
16th to endNight
10%8%36%29%14%
540
May1st to 15thNight
15%5%31%32%13%1
540
16th to endNight
10%324%36%22%2
563
June1st to 15thNight
5%110%40%39%3
540
16th to endNight
418%38%39%6%
540
July1st to 15thNight
5%8%34%44%6%
510
16th to endNight
3430%49%11%
564
August1st to 15thNight
5%15%29%45%12%
539
16th to endNight
10%431%45%6%
573
September1st to 15thNight
11%10%32%40%4
540
16th to endNight
7%111%33%40%5%
539
October1st to 15thNight
11%316%34%29%4
660
16th to endNight
14%5%23%32%21%2
704
November1st to 15thNight
10%8%26%36%17%1
700
16th to endNight
20%9%27%26%14%
768
December1st to 15thNight
22%9%28%30%9%
900
16th to endNight
22%12%29%28%7%
960
Page generated at 2017-09-25 08:02:27. Version ac04

Copyright 2017 A. Danko


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