CopperHead Ridge Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the CopperHead Ridge Observatory clear sky chart from 2005-11-05 to 2017-09-21.

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
48%
15842
23%
46932
15%
15804
56%
15804
29%
29207

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%
718
24%
2327
12%
716
47%
716
25%
1390
January16th to endNight
28%
768
25%
2496
12%
768
44%
768
27%
1506
February1st to 15thNight
29%
701
22%
2287
10%
701
45%
701
26%
1352
February16th to endNight
25%
631
29%
1841
12%
631
43%
631
29%
1111
March1st to 15thNight
35%
720
26%
1980
14%
720
46%
720
30%
1238
March16th to endNight
37%
768
21%
2112
12%
768
45%
768
27%
1385
April1st to 15thNight
39%
718
23%
1888
10%
718
47%
718
34%
1168
April16th to endNight
44%
666
22%
1746
11%
666
50%
666
32%
1122
May1st to 15thNight
47%
540
16%
1620
9%
540
53%
540
27%
1045
May16th to endNight
62%
561
18%
1684
14%
561
64%
561
31%
1046
June1st to 15thNight
64%
540
16%
1620
15%
540
65%
540
29%
1030
June16th to endNight
71%
540
17%
1620
15%
540
73%
540
30%
1019
July1st to 15thNight
72%
510
13%
1530
13%
510
72%
510
28%
988
July16th to endNight
73%
564
16%
1595
14%
531
74%
531
30%
1012
August1st to 15thNight
68%
539
16%
1609
14%
536
68%
536
26%
1087
August16th to endNight
71%
685
18%
1831
14%
685
72%
685
31%
1214
September1st to 15thNight
69%
720
22%
1905
18%
720
70%
720
33%
1213
September16th to endNight
54%
681
20%
1881
18%
681
57%
681
25%
1311
October1st to 15thNight
53%
660
29%
1962
26%
660
60%
660
32%
1191
October16th to endNight
48%
704
35%
2112
23%
704
66%
704
38%
1171
November1st to 15thNight
50%
700
30%
2110
22%
700
61%
700
35%
1202
November16th to endNight
44%
720
28%
2340
19%
720
56%
720
31%
1325
December1st to 15thNight
38%
720
23%
2340
15%
720
49%
720
25%
1452
December16th to endNight
34%
768
23%
2496
15%
768
46%
768
22%
1629

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%244345%5%8%43%
47924
Night
13%5%2442445%7%45%
47129
TransparencyDay
38%5%12%22%17%4
47625
Night
37%411%21%19%5%
46932
SeeingDay
15%418%23%24%14%
5677
Night
15%6%22%32%20%2
15849

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%5%3443435%6%43%
1611
16th to endDay
14%424324345%49%
1728
February1st to 15thDay
14%6%2442345%6%44%
1575
16th to endDay
14%5%24423347%47%
1628
March1st to 15thDay
14%42322435%7%49%
1980
16th to endDay
17%5%2442345%5%44%
2111
April1st to 15thDay
11%41322435%7%52%
2059
16th to endDay
14%415%435%5%47%44%
2224
May1st to 15thDay
13%5%25%5%35%5%6%8%37%
2331
16th to endDay
10%5%35%5%35%5%5%9%41%
2431
June1st to 15thDay
8%415%5%35%6%7%11%39%
2340
16th to endDay
6%4245%45%6%7%11%40%
2340
July1st to 15thDay
8%6%26%6%46%6%7%10%33%
2340
16th to endDay
7%5%26%7%47%7%8%10%32%
2465
August1st to 15thDay
10%6%26%7%46%6%8%10%30%
2340
16th to endDay
10%5%25%6%45%6%8%9%35%
2357
September1st to 15thDay
10%3145%25%6%5%8%44%
2052
16th to endDay
19%7%25%4245%36%39%
1872
October1st to 15thDay
14%424222236%53%
1667
16th to endDay
12%42342333456%
1760
November1st to 15thDay
13%313312336%56%
1745
16th to endDay
14%433433446%48%
1620
December1st to 15thDay
15%7%1432445%6%45%
1620
16th to endDay
20%8%14322345%42%
1728
January1st to 15thNight
16%5%23422445%48%
2327
16th to endNight
16%425%423345%47%
2496
February1st to 15thNight
15%5%23414445%48%
2278
16th to endNight
13%5%24423346%49%
1841
March1st to 15thNight
14%5%24424446%48%
1980
16th to endNight
16%5%25%424346%43%
2112
April1st to 15thNight
11%424423347%50%
1888
16th to endNight
15%4245%23446%46%
1746
May1st to 15thNight
11%6%26%435%36%8%40%
1619
16th to endNight
9%5%244345%7%9%42%
1682
June1st to 15thNight
9%425%5%36%5%7%11%38%
1620
16th to endNight
7%3245%35%6%7%11%40%
1620
July1st to 15thNight
7%5%26%5%36%7%7%12%35%
1620
16th to endNight
5%3246%36%6%8%13%36%
1703
August1st to 15thNight
10%5%26%5%45%6%7%9%35%
1620
16th to endNight
8%5%26%5%35%6%8%10%37%
1831
September1st to 15thNight
8%5%245%2446%9%45%
1905
16th to endNight
16%7%25%5%35%5%5%5%37%
1881
October1st to 15thNight
14%5%24323435%49%
1962
16th to endNight
12%41422223459%
2112
November1st to 15thNight
13%413323335%55%
2110
16th to endNight
14%32421345%6%50%
2340
December1st to 15thNight
15%6%25%424335%45%
2340
16th to endNight
21%6%34323436%39%
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
43%37%21%20%4
1612
16th to endDay
37%26%25%20%7%
1728
February1st to 15thDay
39%37%23%21%4
1577
16th to endDay
36%410%25%18%4
1628
March1st to 15thDay
35%38%24%21%5%
1980
16th to endDay
40%410%22%18%3
2112
April1st to 15thDay
29%310%27%21%6%
2059
16th to endDay
38%411%20%18%6%
2224
May1st to 15thDay
42%417%19%12%3
2331
16th to endDay
38%5%15%25%12%2
2435
June1st to 15thDay
35%5%19%24%13%
2340
16th to endDay
34%7%18%21%15%2
2340
July1st to 15thDay
40%9%16%18%11%3
2201
16th to endDay
40%8%18%19%11%1
2310
August1st to 15thDay
44%7%15%21%9%
2327
16th to endDay
41%7%17%21%10%1
2357
September1st to 15thDay
36%6%13%20%19%3
2052
16th to endDay
45%47%18%20%2
1872
October1st to 15thDay
33%37%27%22%5%
1667
16th to endDay
31%25%24%26%8%
1760
November1st to 15thDay
31%28%18%29%9%
1745
16th to endDay
37%27%23%23%4
1620
December1st to 15thDay
39%49%22%19%5%
1620
16th to endDay
44%310%18%19%3
1728
January1st to 15thNight
38%39%17%23%7%
2327
16th to endNight
39%26%23%21%5%
2496
February1st to 15thNight
37%28%22%23%5%
2287
16th to endNight
36%210%24%22%3
1841
March1st to 15thNight
37%38%23%21%6%
1980
16th to endNight
41%48%22%17%4
2112
April1st to 15thNight
34%39%23%22%5%
1888
16th to endNight
38%311%18%18%8%
1746
May1st to 15thNight
39%5%15%20%16%1
1620
16th to endNight
35%7%16%26%12%1
1684
June1st to 15thNight
38%6%15%23%13%1
1620
16th to endNight
34%8%16%21%14%3
1620
July1st to 15thNight
35%10%17%20%12%3
1530
16th to endNight
34%9%21%20%11%2
1595
August1st to 15thNight
42%7%17%18%13%1
1609
16th to endNight
36%8%19%23%9%1
1831
September1st to 15thNight
34%7%13%20%18%5%
1905
16th to endNight
46%5%9%15%19%3
1881
October1st to 15thNight
37%38%23%22%5%
1962
16th to endNight
30%25%24%26%10%
2112
November1st to 15thNight
32%36%18%26%12%
2110
16th to endNight
33%36%23%25%7%
2340
December1st to 15thNight
41%39%18%20%5%
2340
16th to endNight
45%38%18%19%4
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%32%30%5%
90
16th to endDay
14%14%47%13%9%
96
February1st to 15thDay
14%10%51%18%5%
90
16th to endDay
15%9%37%24%12%
132
March1st to 15thDay
15%9%34%29%10%
270
16th to endDay
19%7%29%31%11%
288
April1st to 15thDay
17%10%26%22%21%2
270
16th to endDay
18%322%24%23%7%
270
May1st to 15thDay
15%6%26%25%15%9%
288
16th to endDay
16%212%17%32%17%
331
June1st to 15thDay
13%210%19%34%20%
315
16th to endDay
10%18%27%27%23%
315
July1st to 15thDay
12%8%23%29%26%
305
16th to endDay
8%1415%35%33%
326
August1st to 15thDay
14%17%20%31%24%
313
16th to endDay
10%15%21%31%30%
332
September1st to 15thDay
13%110%15%32%26%
315
16th to endDay
25%113%20%25%14%
275
October1st to 15thDay
19%318%29%20%9%
255
16th to endDay
13%319%28%27%7%
272
November1st to 15thDay
20%323%22%20%9%
253
16th to endDay
8%8%28%18%27%6%
90
December1st to 15thDay
16%5%34%33%7%2
90
16th to endDay
31%10%27%20%10%
96
January1st to 15thNight
18%10%32%29%7%
720
16th to endNight
19%8%39%29%2
768
February1st to 15thNight
19%11%36%30%2
704
16th to endNight
16%14%38%27%3
631
March1st to 15thNight
17%9%32%33%6%
720
16th to endNight
18%8%28%34%8%
768
April1st to 15thNight
14%9%32%30%12%
718
16th to endNight
17%6%25%32%16%
666
May1st to 15thNight
14%6%25%37%15%
540
16th to endNight
12%213%33%35%3
563
June1st to 15thNight
11%112%34%34%6%
540
16th to endNight
7%27%35%42%5%
540
July1st to 15thNight
8%16%34%42%6%
510
16th to endNight
6%15%29%45%12%
564
August1st to 15thNight
13%15%29%43%6%
539
16th to endNight
10%25%28%45%7%
685
September1st to 15thNight
11%17%32%39%6%
720
16th to endNight
21%211%29%31%3
681
October1st to 15thNight
18%419%30%24%4
660
16th to endNight
15%426%29%21%2
704
November1st to 15thNight
15%5%23%35%17%2
700
16th to endNight
15%8%26%32%15%
720
December1st to 15thNight
19%6%28%35%10%
720
16th to endNight
25%7%25%34%6%
768
Page generated at 2017-09-22 07:35:31. Version ac04

Copyright 2017 A. Danko


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