Rosamond Skypark
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rosamond Skypark clear sky chart from 2005-11-05 to 2017-09-16.

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%
15728
38%
46811
29%
15683
76%
15683
64%
20205

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
61%
716
30%
2491
27%
716
71%
716
47%
1144
January16th to endNight
59%
768
38%
2394
30%
768
70%
768
51%
1134
February1st to 15thNight
61%
700
36%
2105
29%
698
72%
698
54%
986
February16th to endNight
53%
632
33%
1895
27%
632
64%
632
49%
937
March1st to 15thNight
57%
720
31%
2160
25%
720
69%
720
56%
992
March16th to endNight
52%
768
37%
2004
20%
768
67%
768
63%
968
April1st to 15thNight
46%
719
36%
1799
13%
719
60%
719
62%
905
April16th to endNight
49%
720
40%
1800
13%
720
62%
720
74%
824
May1st to 15thNight
53%
606
37%
1685
20%
605
63%
605
78%
677
May16th to endNight
50%
561
37%
1685
19%
561
63%
561
71%
660
June1st to 15thNight
62%
417
38%
1497
30%
417
75%
417
84%
458
June16th to endNight
74%
360
43%
1440
43%
360
84%
360
88%
393
July1st to 15thNight
88%
340
37%
1360
41%
340
92%
340
70%
431
July16th to endNight
88%
568
39%
1592
34%
530
88%
530
71%
657
August1st to 15thNight
84%
717
39%
1790
24%
713
86%
713
87%
766
August16th to endNight
91%
764
47%
1910
30%
764
92%
764
84%
839
September1st to 15thNight
87%
720
45%
1824
32%
720
91%
720
83%
795
September16th to endNight
81%
660
48%
1826
39%
660
89%
660
85%
720
October1st to 15thNight
70%
660
42%
1840
33%
660
81%
660
70%
801
October16th to endNight
73%
704
45%
2143
39%
704
84%
704
71%
854
November1st to 15thNight
74%
700
39%
2275
37%
700
83%
700
66%
912
November16th to endNight
72%
720
39%
2340
38%
720
79%
720
60%
984
December1st to 15thNight
63%
720
36%
2340
30%
720
75%
720
48%
1098
December16th to endNight
56%
768
32%
2616
27%
768
67%
768
42%
1270

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
111212235%75%
47935
Night
111112235%76%
47008
TransparencyDay
11%25%16%28%34%
47624
Night
11%26%19%30%29%
46819
SeeingDay
29%27%31%19%9%
5885
Night
2324%40%25%3
15738

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
5%212324447%62%
1444
16th to endDay
6%414313337%60%
1827
February1st to 15thDay
221221345%8%65%
1751
16th to endDay
431432335%6%61%
1579
March1st to 15thDay
121121247%10%65%
1800
16th to endDay
111221345%9%67%
2217
April1st to 15thDay
1212212246%71%
2149
16th to endDay
1111237%77%
2160
May1st to 15thDay
1111225%82%
2265
16th to endDay
1111126%80%
2429
June1st to 15thDay
11125%84%
2460
16th to endDay
11290%
2520
July1st to 15thDay
1111122481%
2520
16th to endDay
111211113479%
2459
August1st to 15thDay
11111286%
2160
16th to endDay
11122485%
2292
September1st to 15thDay
111112484%
2136
16th to endDay
11111387%
1823
October1st to 15thDay
1111211245%76%
1788
16th to endDay
1112335%78%
1727
November1st to 15thDay
112212236%75%
1584
16th to endDay
213212339%67%
1620
December1st to 15thDay
22143135%5%8%60%
1620
16th to endDay
4223423447%59%
1605
January1st to 15thNight
3213323347%64%
2491
16th to endNight
4413212237%66%
2394
February1st to 15thNight
2213213336%68%
2101
16th to endNight
4213223446%63%
1895
March1st to 15thNight
1212213347%67%
2160
16th to endNight
111221235%8%71%
2004
April1st to 15thNight
221212236%73%
1799
16th to endNight
11111126%81%
1800
May1st to 15thNight
11237%81%
1685
16th to endNight
11223482%
1684
June1st to 15thNight
113487%
1497
16th to endNight
1292%
1440
July1st to 15thNight
111222384%
1440
16th to endNight
1111223479%
1704
August1st to 15thNight
111388%
1800
16th to endNight
122386%
1910
September1st to 15thNight
11111387%
1824
16th to endNight
1112388%
1826
October1st to 15thNight
11111336%77%
1840
16th to endNight
1111135%81%
2143
November1st to 15thNight
111112235%76%
2275
16th to endNight
2112212248%71%
2340
December1st to 15thNight
3312223237%67%
2340
16th to endNight
5%313213348%62%
2616

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
21%48%23%27%14%
1444
16th to endDay
25%29%22%24%16%
1827
February1st to 15thDay
18%37%24%28%17%
1751
16th to endDay
22%38%24%30%10%
1579
March1st to 15thDay
13%310%27%25%19%
1800
16th to endDay
13%411%26%28%16%
2217
April1st to 15thDay
15%27%24%32%17%
2149
16th to endDay
7%18%24%31%25%
2160
May1st to 15thDay
7%16%19%33%30%
2265
16th to endDay
8%15%19%40%24%
2432
June1st to 15thDay
5%1313%27%48%
2460
16th to endDay
415%16%71%
2520
July1st to 15thDay
8%126%17%63%
2371
16th to endDay
11%1311%24%47%
2308
August1st to 15thDay
6%16%21%63%
2146
16th to endDay
6%116%26%58%
2292
September1st to 15thDay
6%129%25%54%
2136
16th to endDay
5%18%33%50%
1823
October1st to 15thDay
10%2415%33%33%
1788
16th to endDay
9%35%14%32%35%
1727
November1st to 15thDay
12%27%18%38%21%
1584
16th to endDay
17%37%21%30%20%
1620
December1st to 15thDay
20%410%23%27%13%
1620
16th to endDay
25%412%24%22%11%
1605
January1st to 15thNight
20%37%22%29%16%
2491
16th to endNight
19%28%22%25%21%
2394
February1st to 15thNight
17%29%21%26%21%
2112
16th to endNight
21%38%24%30%12%
1895
March1st to 15thNight
15%310%25%24%19%
2160
16th to endNight
12%311%30%27%14%
2004
April1st to 15thNight
14%27%33%27%13%
1799
16th to endNight
7%17%30%35%17%
1800
May1st to 15thNight
5%18%25%38%20%
1686
16th to endNight
6%28%21%43%18%
1685
June1st to 15thNight
35%17%31%40%
1497
16th to endNight
227%24%61%
1440
July1st to 15thNight
7%128%18%60%
1360
16th to endNight
9%2414%26%42%
1592
August1st to 15thNight
4119%25%57%
1790
16th to endNight
5%117%32%52%
1910
September1st to 15thNight
5%129%31%49%
1824
16th to endNight
4119%39%43%
1826
October1st to 15thNight
9%2415%35%32%
1840
16th to endNight
8%2414%30%39%
2143
November1st to 15thNight
11%15%18%36%26%
2275
16th to endNight
12%37%21%29%25%
2340
December1st to 15thNight
18%48%22%28%16%
2340
16th to endNight
21%6%11%25%23%13%
2616

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
13%426%30%18%6%
72
16th to endDay
8%12%26%20%20%10%
273
February1st to 15thDay
415%26%23%19%10%
266
16th to endDay
8%16%30%22%13%8%
238
March1st to 15thDay
418%27%20%21%7%
270
16th to endDay
417%29%27%17%4
288
April1st to 15thDay
5%20%32%26%9%5%
269
16th to endDay
222%38%21%9%4
270
May1st to 15thDay
113%35%27%14%6%
288
16th to endDay
212%35%26%14%8%
330
June1st to 15thDay
18%33%34%13%8%
315
16th to endDay
432%33%18%10%
315
July1st to 15thDay
123%41%20%11%
305
16th to endDay
214%48%21%12%
327
August1st to 15thDay
2125%42%15%12%
315
16th to endDay
14%47%21%15%
332
September1st to 15thDay
225%35%26%8%
315
16th to endDay
17%19%30%28%13%
258
October1st to 15thDay
110%30%25%24%6%
255
16th to endDay
26%26%24%26%13%
239
November1st to 15thDay
27%10%21%31%27%
90
16th to endDay
11%20%40%24%4
90
December1st to 15thDay
18%21%28%33%6%
90
16th to endDay
9%17%14%26%28%4
75
January1st to 15thNight
4224%40%23%3
720
16th to endNight
5%326%40%21%2
768
February1st to 15thNight
2427%38%22%4
704
16th to endNight
6%5%32%34%17%3
632
March1st to 15thNight
25%31%38%20%2
720
16th to endNight
26%36%36%17%1
768
April1st to 15thNight
27%40%31%16%1
719
16th to endNight
17%40%32%16%1
720
May1st to 15thNight
5%39%38%14%1
606
16th to endNight
9%38%38%13%
563
June1st to 15thNight
333%51%11%
417
16th to endNight
24%56%18%
360
July1st to 15thNight
17%56%32%1
340
16th to endNight
25%52%37%1
568
August1st to 15thNight
12%47%34%3
717
16th to endNight
6%42%44%6%
764
September1st to 15thNight
19%42%41%5%
720
16th to endNight
115%38%38%5%
660
October1st to 15thNight
1323%38%29%3
660
16th to endNight
1120%34%34%6%
704
November1st to 15thNight
2219%41%29%5%
700
16th to endNight
2219%40%30%4
720
December1st to 15thNight
5%323%39%25%2
720
16th to endNight
6%5%28%37%21%1
768
Page generated at 2017-09-17 09:05:46. Version ac04

Copyright 2017 A. Danko


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