Kitters Angola Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kitters Angola Observatory clear sky chart from 2005-11-05 to 2018-01-12.

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
27%
15376
11%
48412
7%
15337
32%
15337
13%
36691

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
7%
761
4%
2612
2%
761
10%
761
3%
2344
January16th to endNight
9%
768
5%
2496
2%
768
13%
768
4%
2229
February1st to 15thNight
9%
704
4%
2287
2%
701
12%
701
5%
1997
February16th to endNight
13%
631
7%
1998
2%
631
19%
631
6%
1671
March1st to 15thNight
18%
720
11%
1980
5%
720
23%
720
10%
1607
March16th to endNight
23%
768
16%
2112
7%
768
30%
768
17%
1570
April1st to 15thNight
22%
718
13%
1811
5%
718
27%
718
17%
1382
April16th to endNight
35%
599
19%
1679
7%
599
42%
599
25%
1129
May1st to 15thNight
38%
502
15%
1582
11%
502
44%
502
19%
1090
May16th to endNight
44%
374
17%
1497
17%
374
52%
374
21%
891
June1st to 15thNight
44%
360
13%
1440
11%
360
53%
360
19%
906
June16th to endNight
41%
360
11%
1440
13%
360
47%
360
19%
924
July1st to 15thNight
55%
340
15%
1360
21%
340
60%
340
25%
771
July16th to endNight
55%
507
15%
1538
13%
474
58%
474
27%
943
August1st to 15thNight
58%
539
16%
1609
12%
536
61%
536
30%
997
August16th to endNight
56%
648
19%
1794
11%
648
59%
648
32%
1128
September1st to 15thNight
46%
720
19%
1800
10%
720
49%
720
27%
1244
September16th to endNight
47%
717
21%
2007
15%
717
50%
717
26%
1327
October1st to 15thNight
36%
720
14%
2160
11%
720
40%
720
19%
1529
October16th to endNight
15%
768
10%
2304
5%
768
21%
768
10%
1839
November1st to 15thNight
24%
760
15%
2534
12%
760
31%
760
14%
1836
November16th to endNight
15%
780
9%
2730
6%
780
21%
780
8%
2220
December1st to 15thNight
10%
780
3%
2730
1%
780
12%
780
3%
2454
December16th to endNight
6%
832
2%
2912
0%
832
9%
832
2%
2663

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
17%10%47%5%34446%30%
48918
Night
19%13%47%5%24445%27%
48594
Cloud CoverDay
18%11%46%5%34446%29%
48928
Night
19%12%5%7%5%24445%27%
48598
TransparencyDay
54%5%12%17%8%
48618
Night
59%5%10%15%8%1
48412
SeeingDay
25%13%25%20%10%4
5742
Night
27%14%24%21%10%1
15381

By Month

Percentage Cloud Cover NE (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
20%20%8%14%8%2423410%
1568
16th to endDay
14%21%10%15%8%443338%
1728
February1st to 15thDay
18%19%7%16%8%35%32211%
1575
16th to endDay
19%16%7%10%7%3433418%
1473
March1st to 15thDay
19%17%6%8%6%33345%21%
1969
16th to endDay
18%11%46%5%2445%5%30%
2112
April1st to 15thDay
21%11%45%424345%31%
2136
16th to endDay
19%8%35%424346%39%
2292
May1st to 15thDay
19%6%25%43445%7%34%
2367
16th to endDay
14%5%25%43445%8%41%
2618
June1st to 15thDay
17%6%34425%5%5%8%37%
2520
16th to endDay
14%424435%5%6%9%40%
2520
July1st to 15thDay
10%5%2442445%9%45%
2520
16th to endDay
11%5%25%5%35%6%7%9%37%
2521
August1st to 15thDay
11%5%24425%5%6%9%40%
2340
16th to endDay
13%5%1442345%9%44%
2394
September1st to 15thDay
18%5%25%44345%6%37%
2160
16th to endDay
16%5%235%3445%8%39%
1948
October1st to 15thDay
24%7%35%5%33445%32%
1800
16th to endDay
30%11%46%6%3433421%
1920
November1st to 15thDay
18%15%47%434346%26%
1653
16th to endDay
24%21%5%6%42334418%
1560
December1st to 15thDay
22%24%10%11%5%2332210%
1560
16th to endDay
23%25%9%12%5%232237%
1664
January1st to 15thNight
22%22%7%13%8%3322210%
2612
16th to endNight
17%23%8%12%9%4432310%
2496
February1st to 15thNight
18%20%9%14%7%3333312%
2285
16th to endNight
18%15%7%13%7%34435%16%
1998
March1st to 15thNight
21%14%6%7%7%25%34422%
1968
16th to endNight
18%12%37%424345%33%
2112
April1st to 15thNight
23%12%35%423345%31%
1811
16th to endNight
16%6%245%24447%40%
1679
May1st to 15thNight
18%6%25%5%35%5%5%7%33%
1582
16th to endNight
13%5%25%3245%5%7%43%
1495
June1st to 15thNight
15%6%146%35%45%6%40%
1440
16th to endNight
14%5%26%5%35%5%5%7%38%
1440
July1st to 15thNight
7%5%25%5%25%45%9%45%
1440
16th to endNight
11%4135%35%6%6%7%44%
1645
August1st to 15thNight
10%5%24425%5%6%9%43%
1620
16th to endNight
12%5%14425%5%7%8%43%
1794
September1st to 15thNight
19%5%2432345%6%40%
1800
16th to endNight
18%5%245%2345%6%42%
2007
October1st to 15thNight
21%7%25%5%2445%6%34%
2160
16th to endNight
33%9%36%5%23345%21%
2304
November1st to 15thNight
22%12%35%423345%30%
2534
16th to endNight
22%20%6%7%5%2432419%
2730
December1st to 15thNight
24%24%10%9%5%234338%
2730
16th to endNight
24%24%9%12%5%232237%
2912

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
20%20%9%12%9%2333310%
1568
16th to endDay
14%22%10%15%9%343338%
1728
February1st to 15thDay
18%20%7%16%8%4432310%
1575
16th to endDay
18%18%6%12%7%3333417%
1473
March1st to 15thDay
19%17%7%8%5%3334421%
1980
16th to endDay
18%13%46%5%35%446%29%
2111
April1st to 15thDay
22%12%5%4423445%30%
2136
16th to endDay
19%9%24433246%38%
2292
May1st to 15thDay
19%7%26%5%34447%34%
2367
16th to endDay
15%6%2442445%9%39%
2618
June1st to 15thDay
19%6%23425%5%5%8%35%
2520
16th to endDay
15%4245%25%47%10%38%
2520
July1st to 15thDay
11%5%2443445%9%44%
2520
16th to endDay
12%425%5%347%7%9%36%
2521
August1st to 15thDay
12%425%435%5%7%9%39%
2340
16th to endDay
14%5%2342445%9%42%
2394
September1st to 15thDay
19%5%25%5%34446%36%
2160
16th to endDay
16%5%24435%45%7%39%
1948
October1st to 15thDay
25%7%26%5%23346%31%
1800
16th to endDay
31%11%37%5%2434421%
1920
November1st to 15thDay
18%15%5%6%5%34345%26%
1653
16th to endDay
25%21%5%6%42334318%
1560
December1st to 15thDay
22%25%10%11%5%2322211%
1560
16th to endDay
22%26%10%12%5%233237%
1664
January1st to 15thNight
22%21%8%13%8%2322210%
2612
16th to endNight
17%22%8%13%9%3432211%
2496
February1st to 15thNight
17%21%8%14%8%3332312%
2278
16th to endNight
17%16%8%13%8%3433415%
1998
March1st to 15thNight
21%14%6%8%6%3433422%
1980
16th to endNight
18%12%46%5%2434432%
2112
April1st to 15thNight
24%13%34333345%30%
1811
16th to endNight
17%6%15%5%24346%40%
1679
May1st to 15thNight
19%6%25%445%447%33%
1581
16th to endNight
13%5%244245%5%7%42%
1495
June1st to 15thNight
16%5%245%445%5%6%40%
1440
16th to endNight
15%5%25%5%25%5%5%8%37%
1440
July1st to 15thNight
9%425%5%35%5%5%8%45%
1440
16th to endNight
11%4135%246%6%7%44%
1645
August1st to 15thNight
10%424425%5%6%8%43%
1620
16th to endNight
12%5%233245%7%8%43%
1794
September1st to 15thNight
20%5%2432445%6%40%
1800
16th to endNight
18%5%145%2345%6%42%
2007
October1st to 15thNight
22%6%25%5%24346%34%
2160
16th to endNight
33%9%36%5%23345%21%
2304
November1st to 15thNight
22%11%35%423345%31%
2534
16th to endNight
21%20%6%7%434335%19%
2730
December1st to 15thNight
24%24%10%10%5%233249%
2730
16th to endNight
24%24%10%12%5%233227%
2912

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
79%46%7%2
1569
16th to endDay
80%48%41
1728
February1st to 15thDay
81%36%5%2
1577
16th to endDay
70%49%11%3
1473
March1st to 15thDay
65%411%13%4
1980
16th to endDay
56%48%19%9%
2112
April1st to 15thDay
55%312%17%9%
2136
16th to endDay
47%310%20%15%2
2292
May1st to 15thDay
48%5%12%22%10%
2367
16th to endDay
41%6%15%22%12%1
2622
June1st to 15thDay
44%6%14%22%11%
2520
16th to endDay
39%7%17%22%12%
2520
July1st to 15thDay
37%414%26%15%1
2371
16th to endDay
41%8%16%21%11%
2365
August1st to 15thDay
39%6%17%23%11%1
2327
16th to endDay
37%417%27%11%1
2394
September1st to 15thDay
47%5%12%23%10%
2160
16th to endDay
42%6%12%23%13%
1948
October1st to 15thDay
54%5%11%16%11%1
1800
16th to endDay
67%413%10%3
1920
November1st to 15thDay
60%410%14%8%1
1653
16th to endDay
70%49%10%4
1560
December1st to 15thDay
81%36%7%
1560
16th to endDay
83%47%4
1664
January1st to 15thNight
81%36%43
2612
16th to endNight
80%36%6%2
2496
February1st to 15thNight
78%37%8%2
2287
16th to endNight
71%48%11%3
1998
March1st to 15thNight
65%5%8%15%4
1980
16th to endNight
54%49%16%13%1
2112
April1st to 15thNight
56%49%19%10%
1811
16th to endNight
43%411%20%15%3
1679
May1st to 15thNight
48%5%10%22%10%1
1582
16th to endNight
39%6%13%22%15%2
1497
June1st to 15thNight
42%6%11%23%14%
1440
16th to endNight
43%7%12%21%13%1
1440
July1st to 15thNight
35%6%11%25%18%2
1360
16th to endNight
36%8%14%24%13%2
1538
August1st to 15thNight
35%7%16%28%11%1
1609
16th to endNight
35%6%15%28%12%1
1794
September1st to 15thNight
43%5%12%22%14%2
1800
16th to endNight
42%5%11%24%15%1
2007
October1st to 15thNight
49%6%11%16%14%1
2160
16th to endNight
64%5%12%13%3
2304
November1st to 15thNight
55%410%17%8%3
2534
16th to endNight
69%39%13%3
2730
December1st to 15thNight
80%5%7%41
2730
16th to endNight
83%46%5%
2912

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
33%36%17%7%4
90
16th to endDay
38%27%27%43
96
February1st to 15thDay
41%36%20%2
90
16th to endDay
30%22%36%8%
114
March1st to 15thDay
34%18%25%16%4
270
16th to endDay
31%18%26%17%41
288
April1st to 15thDay
34%18%25%14%5%1
270
16th to endDay
26%11%29%17%10%3
270
May1st to 15thDay
32%10%26%20%7%2
288
16th to endDay
18%11%31%23%10%4
331
June1st to 15thDay
25%10%29%20%11%2
315
16th to endDay
21%11%28%27%9%1
315
July1st to 15thDay
15%6%25%30%15%6%
305
16th to endDay
13%9%28%26%14%6%
326
August1st to 15thDay
14%5%25%25%18%10%
313
16th to endDay
18%423%25%19%9%
332
September1st to 15thDay
16%7%22%28%15%7%
315
16th to endDay
19%9%16%21%20%12%
314
October1st to 15thDay
23%10%24%19%16%5%
315
16th to endDay
40%15%22%16%5%
336
November1st to 15thDay
26%15%30%20%5%2
173
16th to endDay
43%21%18%16%
90
December1st to 15thDay
44%24%15%10%41
90
16th to endDay
48%22%26%2
96
January1st to 15thNight
37%24%25%10%2
765
16th to endNight
32%24%27%13%2
768
February1st to 15thNight
33%24%25%13%2
704
16th to endNight
29%21%28%18%1
631
March1st to 15thNight
32%18%25%18%4
720
16th to endNight
25%14%32%18%8%1
768
April1st to 15thNight
33%14%25%20%5%
718
16th to endNight
21%10%28%28%8%1
599
May1st to 15thNight
24%6%21%35%10%1
502
16th to endNight
13%8%28%31%14%2
375
June1st to 15thNight
18%6%25%33%14%1
360
16th to endNight
17%7%28%33%12%
360
July1st to 15thNight
9%5%21%41%22%1
340
16th to endNight
13%322%35%23%2
507
August1st to 15thNight
11%320%36%24%3
539
16th to endNight
14%5%18%30%27%3
648
September1st to 15thNight
21%5%20%26%22%3
720
16th to endNight
19%7%18%23%23%6%
717
October1st to 15thNight
26%9%23%21%16%1
720
16th to endNight
38%16%25%15%4
768
November1st to 15thNight
29%14%26%19%6%1
760
16th to endNight
38%18%24%11%6%
780
December1st to 15thNight
42%24%18%11%3
780
16th to endNight
40%25%22%10%1
832
Page generated at 2018-01-12 22:01:31. Version ac04

Copyright 2018 A. Danko


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