Observatorio Villa de Miramar
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatorio Villa de Miramar clear sky chart from 2005-11-05 to 2017-10-06.

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
0%
1945
0%
12403
0%
1031
0%
1031
57%
22052

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
0%
125
0%
466
0%
48
0%
48
58%
998
January16th to endNight
0%
189
0%
725
0%
87
0%
87
46%
1201
February1st to 15thNight
0%
139
0%
446
0%
59
0%
59
59%
956
February16th to endNight
0%
137
0%
413
0%
63
0%
63
57%
869
March1st to 15thNight
0%
162
0%
442
0%
70
0%
70
59%
971
March16th to endNight
0%
99
0%
393
0%
49
0%
49
66%
976
April1st to 15thNight
0%
103
0%
357
0%
37
0%
37
66%
918
April16th to endNight
0%
57
0%
205
0%
8
0%
8
75%
669
May1st to 15thNight
0%
44
0%
219
0%
13
0%
13
72%
669
May16th to endNight
0%
15
0%
106
0%
7
0%
7
86%
615
June1st to 15thNight
0%
14
0%
169
0%
11
0%
11
79%
626
June16th to endNight
0%
8
0%
346
0%
8
0%
8
66%
706
July1st to 15thNight
0%
17
0%
779
0%
16
0%
16
41%
848
July16th to endNight
0%
42
0%
1170
0%
39
0%
39
25%
1068
August1st to 15thNight
0%
28
0%
943
0%
28
0%
28
35%
952
August16th to endNight
0%
44
0%
1104
0%
44
0%
44
40%
1144
September1st to 15thNight
0%
71
0%
921
0%
71
0%
71
43%
1119
September16th to endNight
0%
39
0%
426
0%
36
0%
36
65%
913
October1st to 15thNight
0%
62
0%
401
0%
48
0%
48
64%
889
October16th to endNight
0%
56
0%
263
0%
32
0%
32
75%
841
November1st to 15thNight
0%
68
0%
316
0%
38
0%
38
70%
875
November16th to endNight
0%
118
0%
520
0%
55
0%
55
55%
1026
December1st to 15thNight
0%
128
0%
604
0%
73
0%
73
53%
1061
December16th to endNight
0%
180
0%
669
0%
91
0%
91
52%
1142

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
TransparencyDay
15%37%14%23%35%
47738
Night
16%36%12%23%38%
47153
SeeingDay
39%27%43%14%
5602
Night
37%28%41%17%
15798

By Month

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
12%1314%26%41%
1612
16th to endDay
22%2311%24%33%
1728
February1st to 15thDay
14%235%28%44%
1751
16th to endDay
15%1310%28%40%
1689
March1st to 15thDay
17%127%25%45%
1980
16th to endDay
12%127%23%52%
2112
April1st to 15thDay
14%115%25%50%
1970
16th to endDay
10%116%21%58%
2150
May1st to 15thDay
8%116%22%60%
2214
16th to endDay
41426%62%
2432
June1st to 15thDay
6%27%28%53%
2340
16th to endDay
10%37%16%36%26%
2340
July1st to 15thDay
26%11%17%23%14%6%
2201
16th to endDay
31%12%23%26%41
2312
August1st to 15thDay
22%9%22%30%10%4
2319
16th to endDay
23%10%19%26%15%4
2170
September1st to 15thDay
23%7%12%26%20%9%
1980
16th to endDay
11%37%19%35%23%
1980
October1st to 15thDay
13%26%17%25%34%
1794
16th to endDay
9%1310%25%48%
1760
November1st to 15thDay
10%139%28%47%
1759
16th to endDay
15%2313%23%42%
1797
December1st to 15thDay
18%25%12%29%33%
1620
16th to endDay
19%16%11%28%32%
1728
January1st to 15thNight
15%1211%24%43%
2327
16th to endNight
23%1311%25%34%
2493
February1st to 15thNight
16%127%24%46%
2112
16th to endNight
19%126%29%40%
1784
March1st to 15thNight
18%127%23%47%
1980
16th to endNight
13%136%21%53%
2112
April1st to 15thNight
14%126%22%52%
1978
16th to endNight
8%25%20%61%
1809
May1st to 15thNight
9%2419%62%
1734
16th to endNight
41223%67%
1685
June1st to 15thNight
7%25%21%61%
1620
16th to endNight
11%36%13%29%35%
1620
July1st to 15thNight
21%11%18%25%15%7%
1530
16th to endNight
36%13%23%20%41
1593
August1st to 15thNight
26%11%20%24%12%4
1617
16th to endNight
24%9%20%25%14%5%
2027
September1st to 15thNight
24%7%14%21%23%8%
1980
16th to endNight
12%35%19%29%30%
1980
October1st to 15thNight
14%1415%26%38%
1962
16th to endNight
8%1211%24%51%
2112
November1st to 15thNight
10%128%28%47%
2100
16th to endNight
18%138%24%43%
2162
December1st to 15thNight
18%2412%25%35%
2340
16th to endNight
19%25%12%28%32%
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
110%53%32%3
90
16th to endDay
1214%40%37%4
96
February1st to 15thDay
3221%36%30%4
266
16th to endDay
6%123%42%16%9%
238
March1st to 15thDay
3221%34%31%5%
270
16th to endDay
2116%40%27%10%
288
April1st to 15thDay
4118%42%27%4
269
16th to endDay
120%33%34%10%
270
May1st to 15thDay
2121%36%30%7%
288
16th to endDay
10%37%44%6%
330
June1st to 15thDay
1327%57%10%
315
16th to endDay
3215%60%16%
315
July1st to 15thDay
4117%57%17%
305
16th to endDay
6%114%49%27%
327
August1st to 15thDay
211%54%30%
315
16th to endDay
310%56%28%
332
September1st to 15thDay
7%116%52%21%
315
16th to endDay
5%220%53%17%
315
October1st to 15thDay
45%23%46%19%
196
16th to endDay
5%19%43%31%
96
November1st to 15thDay
5%11%35%34%13%
90
16th to endDay
5%114%33%36%8%
90
December1st to 15thDay
111%23%41%23%
90
16th to endDay
15%49%47%21%1
96
January1st to 15thNight
313%45%33%3
720
16th to endNight
6%116%42%29%3
768
February1st to 15thNight
3114%42%32%4
704
16th to endNight
416%49%24%4
632
March1st to 15thNight
5%17%38%34%4
720
16th to endNight
29%37%41%7%
768
April1st to 15thNight
310%43%36%5%
719
16th to endNight
19%39%42%8%
549
May1st to 15thNight
16%39%44%8%
540
16th to endNight
122%60%14%
563
June1st to 15thNight
1114%64%18%
540
16th to endNight
5%58%34%
540
July1st to 15thNight
118%47%40%
510
16th to endNight
5%17%42%42%
564
August1st to 15thNight
45%35%53%
539
16th to endNight
416%40%46%
690
September1st to 15thNight
7%17%41%41%
720
16th to endNight
4110%56%27%
716
October1st to 15thNight
5%326%46%17%
684
16th to endNight
2423%53%15%
704
November1st to 15thNight
27%34%42%14%
700
16th to endNight
410%35%39%8%
720
December1st to 15thNight
5%11%39%35%7%
720
16th to endNight
6%116%45%24%6%
768
Page generated at 2017-10-07 11:07:52. Version ac04

Copyright 2017 A. Danko


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