Rainbow Springs Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rainbow Springs Observatory clear sky chart from 2005-11-05 to 2017-09-20.

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
59%
15841
21%
46981
17%
15802
64%
15802
30%
29143

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
45%
717
21%
2327
16%
716
54%
716
26%
1437
January16th to endNight
42%
768
24%
2424
17%
768
52%
768
27%
1480
February1st to 15thNight
44%
701
26%
2106
18%
699
53%
699
33%
1252
February16th to endNight
44%
631
23%
1872
13%
631
54%
631
29%
1158
March1st to 15thNight
50%
720
29%
1980
17%
720
59%
720
40%
1132
March16th to endNight
52%
768
27%
2112
19%
768
58%
768
39%
1212
April1st to 15thNight
54%
718
24%
1976
16%
718
60%
718
40%
1154
April16th to endNight
60%
678
28%
1826
19%
678
66%
678
45%
1023
May1st to 15thNight
72%
539
26%
1619
20%
539
77%
539
43%
864
May16th to endNight
76%
561
25%
1682
21%
561
77%
561
39%
958
June1st to 15thNight
68%
540
14%
1620
13%
540
68%
540
25%
1098
June16th to endNight
76%
540
10%
1620
8%
540
76%
540
25%
1101
July1st to 15thNight
76%
510
8%
1530
8%
510
76%
510
20%
1114
July16th to endNight
77%
564
7%
1595
7%
531
78%
531
24%
1100
August1st to 15thNight
73%
539
5%
1639
6%
536
74%
536
22%
1163
August16th to endNight
68%
678
10%
2015
11%
678
68%
678
21%
1425
September1st to 15thNight
65%
720
8%
1980
8%
720
65%
720
20%
1436
September16th to endNight
59%
677
15%
1870
15%
677
61%
677
21%
1346
October1st to 15thNight
68%
660
27%
1853
26%
660
71%
660
35%
1123
October16th to endNight
62%
704
29%
2112
27%
704
68%
704
35%
1225
November1st to 15thNight
58%
700
31%
2101
25%
700
67%
700
40%
1143
November16th to endNight
49%
720
28%
2286
20%
720
60%
720
32%
1316
December1st to 15thNight
50%
720
27%
2340
24%
720
57%
720
30%
1378
December16th to endNight
53%
768
23%
2496
21%
768
59%
768
28%
1505

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
9%5%25%5%36%6%6%9%38%
47845
Night
8%4245%345%6%9%45%
47187
TransparencyDay
39%9%14%17%13%6%
47546
Night
34%8%15%19%15%6%
46990
SeeingDay
9%312%21%26%26%
5705
Night
10%318%32%27%7%
15850

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
10%6%35%5%246%48%41%
1611
16th to endDay
10%6%25%424447%46%
1799
February1st to 15thDay
14%6%25%333446%47%
1750
16th to endDay
9%6%25%424447%48%
1601
March1st to 15thDay
8%42442445%8%52%
1980
16th to endDay
8%325%4245%48%49%
2111
April1st to 15thDay
6%3244345%6%9%49%
1972
16th to endDay
6%3244245%6%8%51%
2142
May1st to 15thDay
6%313425%46%9%51%
2331
16th to endDay
6%325%6%35%6%7%10%41%
2431
June1st to 15thDay
11%5%36%7%47%8%7%9%29%
2340
16th to endDay
7%5%36%7%49%8%8%11%27%
2340
July1st to 15thDay
9%5%46%8%5%8%9%9%10%22%
2340
16th to endDay
7%7%38%8%6%9%9%8%9%20%
2465
August1st to 15thDay
10%6%26%8%49%8%10%13%18%
2307
16th to endDay
10%6%37%7%5%8%7%8%11%22%
2173
September1st to 15thDay
10%6%27%7%5%7%8%8%9%25%
1980
16th to endDay
11%7%47%8%47%6%6%9%25%
1859
October1st to 15thDay
9%6%36%7%4445%7%41%
1777
16th to endDay
8%5%25%5%24447%50%
1760
November1st to 15thDay
6%41342445%7%53%
1757
16th to endDay
9%5%14425%446%49%
1671
December1st to 15thDay
10%6%35%42445%7%44%
1620
16th to endDay
8%5%25%436%5%6%8%43%
1728
January1st to 15thNight
12%6%25%5%2346%9%40%
2327
16th to endNight
14%5%2332446%8%43%
2424
February1st to 15thNight
11%5%24323346%51%
2103
16th to endNight
9%6%25%5%235%5%7%46%
1872
March1st to 15thNight
6%31442445%7%54%
1980
16th to endNight
7%42442335%6%55%
2112
April1st to 15thNight
7%42232446%7%54%
1976
16th to endNight
6%31332345%8%57%
1826
May1st to 15thNight
5%21232445%10%57%
1619
16th to endNight
5%31342446%10%51%
1682
June1st to 15thNight
10%426%6%36%5%7%11%36%
1620
16th to endNight
6%425%5%36%6%8%15%34%
1620
July1st to 15thNight
44247%47%8%9%14%31%
1620
16th to endNight
4325%7%47%7%10%15%30%
1703
August1st to 15thNight
6%426%6%46%8%9%11%32%
1650
16th to endNight
9%5%246%47%6%7%11%33%
2015
September1st to 15thNight
7%7%36%6%45%8%7%11%31%
1980
16th to endNight
10%6%37%7%46%5%6%10%31%
1870
October1st to 15thNight
7%4144335%6%7%50%
1853
16th to endNight
8%5%24423447%51%
2112
November1st to 15thNight
6%424325%447%55%
2101
16th to endNight
8%4245%3445%6%50%
2286
December1st to 15thNight
10%5%35%334448%46%
2340
16th to endNight
9%435%5%25%45%8%43%
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
39%5%8%18%18%8%
1612
16th to endDay
36%48%17%22%10%
1799
February1st to 15thDay
38%46%13%20%15%
1752
16th to endDay
35%5%10%15%22%11%
1601
March1st to 15thDay
30%411%23%21%8%
1980
16th to endDay
33%5%11%21%17%10%
2112
April1st to 15thDay
29%7%12%18%22%9%
1972
16th to endDay
27%6%12%21%21%9%
2142
May1st to 15thDay
28%7%12%23%19%8%
2331
16th to endDay
34%8%16%21%15%3
2435
June1st to 15thDay
45%12%16%19%5%
2340
16th to endDay
45%13%20%15%4
2340
July1st to 15thDay
49%14%23%10%1
2201
16th to endDay
51%15%20%10%1
2310
August1st to 15thDay
48%17%23%8%1
2294
16th to endDay
50%14%19%13%1
2173
September1st to 15thDay
49%15%19%10%5%
1980
16th to endDay
51%11%11%15%7%3
1859
October1st to 15thDay
40%5%9%14%17%11%
1777
16th to endDay
33%6%7%14%23%15%
1760
November1st to 15thDay
28%5%11%22%20%12%
1757
16th to endDay
34%48%18%20%12%
1671
December1st to 15thDay
37%6%11%19%18%6%
1620
16th to endDay
35%6%12%22%14%8%
1728
January1st to 15thNight
38%5%10%20%17%8%
2327
16th to endNight
37%5%8%14%23%9%
2424
February1st to 15thNight
34%47%17%19%16%
2112
16th to endNight
36%6%10%15%21%9%
1872
March1st to 15thNight
27%5%12%25%20%8%
1980
16th to endNight
28%411%24%19%11%
2112
April1st to 15thNight
26%7%13%21%23%7%
1976
16th to endNight
24%5%13%28%20%7%
1826
May1st to 15thNight
23%6%16%26%19%7%
1620
16th to endNight
25%8%17%25%20%2
1684
June1st to 15thNight
39%11%21%22%5%
1620
16th to endNight
36%14%24%21%3
1620
July1st to 15thNight
38%19%27%13%1
1530
16th to endNight
36%15%33%11%2
1595
August1st to 15thNight
37%17%32%11%
1639
16th to endNight
41%14%24%16%2
2015
September1st to 15thNight
41%15%24%13%4
1980
16th to endNight
45%10%15%16%8%2
1870
October1st to 15thNight
30%8%12%18%20%9%
1853
16th to endNight
32%48%15%26%12%
2112
November1st to 15thNight
28%310%24%22%10%
2101
16th to endNight
33%49%19%17%15%
2286
December1st to 15thNight
35%5%10%27%15%6%
2340
16th to endNight
36%5%12%21%14%9%
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
13%6%34%23%13%8%
90
16th to endDay
12%14%37%20%12%2
96
February1st to 15thDay
8%20%24%21%22%3
90
16th to endDay
7%7%39%27%16%
102
March1st to 15thDay
7%7%31%35%16%2
270
16th to endDay
11%425%26%28%3
288
April1st to 15thDay
7%6%20%31%28%5%
270
16th to endDay
4217%26%36%12%
270
May1st to 15thDay
5%312%26%30%21%
288
16th to endDay
6%25%18%32%35%
331
June1st to 15thDay
15%5%14%23%40%
315
16th to endDay
6%210%27%51%
315
July1st to 15thDay
5%5%24%62%
305
16th to endDay
7%148%22%54%
326
August1st to 15thDay
11%1310%19%53%
313
16th to endDay
11%49%23%50%
332
September1st to 15thDay
16%314%28%36%
315
16th to endDay
11%5%17%37%28%
270
October1st to 15thDay
10%19%36%28%13%
255
16th to endDay
8%117%34%30%6%
272
November1st to 15thDay
8%214%40%26%9%
265
16th to endDay
7%228%33%21%7%
141
December1st to 15thDay
46%41%31%16%
90
16th to endDay
8%6%18%41%20%4
96
January1st to 15thNight
15%6%26%34%15%
720
16th to endNight
16%8%28%35%11%
768
February1st to 15thNight
14%431%35%12%1
704
16th to endNight
12%7%30%40%8%
631
March1st to 15thNight
8%6%30%40%14%
720
16th to endNight
8%5%28%38%18%
768
April1st to 15thNight
8%328%41%17%
718
16th to endNight
7%224%42%20%1
678
May1st to 15thNight
5%212%48%27%2
540
16th to endNight
6%19%36%37%8%
563
June1st to 15thNight
12%6%26%40%12%
540
16th to endNight
8%415%45%26%
540
July1st to 15thNight
6%1213%40%36%
510
16th to endNight
4110%57%25%
564
August1st to 15thNight
6%28%51%29%
539
16th to endNight
12%1415%44%21%
678
September1st to 15thNight
10%15%22%42%17%
720
16th to endNight
13%8%29%39%8%
677
October1st to 15thNight
8%110%39%35%3
660
16th to endNight
10%316%39%27%2
704
November1st to 15thNight
8%323%40%21%2
700
16th to endNight
10%429%36%18%1
720
December1st to 15thNight
11%5%25%37%18%1
720
16th to endNight
11%5%22%38%20%1
768
Page generated at 2017-09-21 07:18:15. Version ac04

Copyright 2017 A. Danko


Rainbow Springs Observatory Clear Sky Chart | Charts Home