Can del Tajo
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Can del Tajo 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
71%
16193
39%
47051
29%
16150
79%
16150
59%
21144

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
64%
719
32%
2327
27%
716
74%
716
43%
1114
January16th to endNight
59%
768
39%
2331
28%
768
74%
768
46%
1126
February1st to 15thNight
64%
700
37%
2110
29%
699
77%
699
50%
991
February16th to endNight
52%
632
33%
1895
27%
632
64%
632
39%
989
March1st to 15thNight
60%
720
35%
2120
27%
720
73%
720
51%
999
March16th to endNight
63%
768
37%
2112
26%
768
74%
768
55%
1018
April1st to 15thNight
53%
719
39%
1799
17%
719
67%
719
56%
893
April16th to endNight
59%
720
42%
1800
18%
720
72%
720
74%
804
May1st to 15thNight
64%
545
42%
1625
24%
545
75%
545
66%
667
May16th to endNight
67%
562
44%
1685
28%
561
76%
561
75%
632
June1st to 15thNight
73%
540
37%
1620
29%
540
77%
540
78%
625
June16th to endNight
85%
540
39%
1620
34%
540
87%
540
83%
603
July1st to 15thNight
88%
510
31%
1530
26%
510
89%
510
68%
639
July16th to endNight
88%
585
35%
1613
28%
551
89%
551
59%
744
August1st to 15thNight
92%
717
36%
1790
24%
713
93%
713
72%
853
August16th to endNight
89%
764
43%
1910
30%
764
90%
764
71%
915
September1st to 15thNight
87%
720
38%
1915
31%
720
90%
720
70%
874
September16th to endNight
83%
692
48%
1914
40%
692
89%
692
79%
783
October1st to 15thNight
72%
660
43%
1815
33%
660
82%
660
66%
817
October16th to endNight
80%
704
45%
2069
38%
704
88%
704
69%
864
November1st to 15thNight
75%
700
38%
2275
35%
700
85%
700
61%
917
November16th to endNight
68%
720
41%
2340
37%
720
80%
720
58%
973
December1st to 15thNight
66%
720
37%
2340
33%
720
76%
720
48%
1080
December16th to endNight
55%
768
35%
2496
28%
768
69%
768
40%
1224

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
111213346%71%
47870
Night
111212336%75%
47250
TransparencyDay
13%5%5%11%25%38%
47568
Night
11%45%12%26%38%
47054
SeeingDay
212%24%34%19%6%
5881
Night
17%16%28%33%12%
16200

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
121231345%7%65%
1611
16th to endDay
411221335%8%64%
1891
February1st to 15thDay
2111313448%67%
1751
16th to endDay
123245%5%10%62%
1579
March1st to 15thDay
1112223337%70%
1839
16th to endDay
12213346%71%
2112
April1st to 15thDay
112213435%74%
2146
16th to endDay
1111225%82%
2160
May1st to 15thDay
111212237%76%
2323
16th to endDay
11122485%
2429
June1st to 15thDay
111225%83%
2340
16th to endDay
111112285%
2340
July1st to 15thDay
221232445%6%62%
2340
16th to endDay
22135%347%8%10%50%
2443
August1st to 15thDay
12122245%5%7%64%
2160
16th to endDay
421232446%5%62%
2292
September1st to 15thDay
3213324446%65%
2043
16th to endDay
2111122281%
1904
October1st to 15thDay
21224478%
1815
16th to endDay
11112235%79%
1800
November1st to 15thDay
2212345%76%
1584
16th to endDay
111212336%74%
1620
December1st to 15thDay
21232446%9%61%
1620
16th to endDay
111132336%8%65%
1728
January1st to 15thNight
1112245%5%8%64%
2327
16th to endNight
3113312336%68%
2331
February1st to 15thNight
112223437%70%
2101
16th to endNight
1113435%5%5%6%64%
1895
March1st to 15thNight
211223347%70%
2120
16th to endNight
112113347%71%
2112
April1st to 15thNight
12212235%77%
1799
16th to endNight
11115%85%
1800
May1st to 15thNight
112235%80%
1625
16th to endNight
1112288%
1684
June1st to 15thNight
11112485%
1620
16th to endNight
111289%
1620
July1st to 15thNight
111212136%76%
1620
16th to endNight
1112223438%67%
1722
August1st to 15thNight
11112246%76%
1800
16th to endNight
1111112235%76%
1910
September1st to 15thNight
11211222479%
1915
16th to endNight
111111287%
1914
October1st to 15thNight
11112235%79%
1815
16th to endNight
1111235%79%
2069
November1st to 15thNight
1113235%78%
2275
16th to endNight
1212111235%76%
2340
December1st to 15thNight
11122345%8%67%
2340
16th to endNight
32322345%7%65%
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
17%6%7%12%27%28%
1612
16th to endDay
16%7%6%17%27%24%
1891
February1st to 15thDay
15%5%6%12%28%31%
1751
16th to endDay
16%10%7%14%31%20%
1579
March1st to 15thDay
13%5%412%29%33%
1839
16th to endDay
13%6%5%12%33%28%
2112
April1st to 15thDay
12%5%410%40%27%
2146
16th to endDay
6%3313%30%43%
2160
May1st to 15thDay
9%327%28%47%
2323
16th to endDay
5%239%30%48%
2432
June1st to 15thDay
5%226%20%61%
2340
16th to endDay
7%21312%73%
2340
July1st to 15thDay
20%46%11%17%39%
2201
16th to endDay
21%9%11%20%19%17%
2290
August1st to 15thDay
17%5%7%15%22%32%
2146
16th to endDay
18%6%7%11%24%30%
2292
September1st to 15thDay
18%6%6%10%21%36%
2043
16th to endDay
9%325%24%54%
1904
October1st to 15thDay
8%45%9%29%42%
1815
16th to endDay
8%449%24%49%
1800
November1st to 15thDay
10%5%412%27%39%
1584
16th to endDay
11%5%5%12%27%37%
1620
December1st to 15thDay
17%8%7%17%21%27%
1620
16th to endDay
16%7%9%19%27%19%
1728
January1st to 15thNight
15%9%5%14%24%29%
2327
16th to endNight
17%5%7%14%23%31%
2331
February1st to 15thNight
14%6%7%12%24%34%
2112
16th to endNight
17%10%7%11%27%24%
1895
March1st to 15thNight
14%5%5%12%30%32%
2120
16th to endNight
12%5%6%13%30%31%
2112
April1st to 15thNight
11%4411%33%34%
1799
16th to endNight
5%2411%32%44%
1800
May1st to 15thNight
7%338%26%50%
1626
16th to endNight
4217%32%51%
1685
June1st to 15thNight
5%12422%62%
1620
16th to endNight
411410%77%
1620
July1st to 15thNight
10%2414%21%46%
1530
16th to endNight
13%48%25%27%20%
1613
August1st to 15thNight
9%3418%29%34%
1790
16th to endNight
11%25%12%31%36%
1910
September1st to 15thNight
9%349%26%45%
1915
16th to endNight
6%126%28%54%
1914
October1st to 15thNight
9%3311%27%44%
1815
16th to endNight
7%4411%22%49%
2069
November1st to 15thNight
9%45%11%32%37%
2275
16th to endNight
11%3413%28%37%
2340
December1st to 15thNight
13%7%8%17%25%26%
2340
16th to endNight
17%8%8%19%24%21%
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
7%23%22%35%11%
90
16th to endDay
326%27%27%13%1
259
February1st to 15thDay
315%29%34%15%1
266
16th to endDay
424%31%28%7%2
238
March1st to 15thDay
220%32%27%13%2
270
16th to endDay
122%31%27%12%4
288
April1st to 15thDay
223%34%23%13%3
269
16th to endDay
122%35%27%11%2
270
May1st to 15thDay
218%30%32%11%3
288
16th to endDay
116%31%35%11%3
330
June1st to 15thDay
19%33%33%15%5%
315
16th to endDay
1319%46%22%6%
315
July1st to 15thDay
3111%35%37%10%
305
16th to endDay
46%34%36%17%
327
August1st to 15thDay
111%39%30%15%
315
16th to endDay
5%6%39%33%14%
332
September1st to 15thDay
5%218%40%25%7%
315
16th to endDay
36%27%42%17%3
288
October1st to 15thDay
114%32%33%17%1
255
16th to endDay
37%18%38%26%5%
180
November1st to 15thDay
15%14%35%23%11%
90
16th to endDay
21%28%26%18%4
90
December1st to 15thDay
214%18%28%30%5%
90
16th to endDay
26%31%29%13%
96
January1st to 15thNight
211%18%33%24%10%
720
16th to endNight
312%19%32%25%6%
768
February1st to 15thNight
10%19%34%27%6%
704
16th to endNight
116%26%31%17%6%
632
March1st to 15thNight
212%22%34%21%6%
720
16th to endNight
111%21%32%24%8%
768
April1st to 15thNight
117%25%29%20%5%
719
16th to endNight
10%28%29%23%7%
720
May1st to 15thNight
9%23%32%26%6%
546
16th to endNight
9%21%30%31%7%
563
June1st to 15thNight
321%36%30%7%
540
16th to endNight
110%37%40%8%
540
July1st to 15thNight
2420%57%13%
510
16th to endNight
21217%58%18%
585
August1st to 15thNight
1217%51%27%
717
16th to endNight
2214%51%28%
764
September1st to 15thNight
115%17%54%19%
720
16th to endNight
1112%26%44%14%
692
October1st to 15thNight
16%16%33%31%9%
660
16th to endNight
314%27%36%18%
704
November1st to 15thNight
16%14%34%30%12%
700
16th to endNight
37%17%26%27%16%
720
December1st to 15thNight
210%17%33%27%9%
720
16th to endNight
415%20%31%19%8%
768
Page generated at 2017-09-25 06:02:25. Version ac04

Copyright 2017 A. Danko


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