Fleischmann Planetarium and Science Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fleischmann Planetarium and Science Center clear sky chart from 2005-11-05 to 2017-09-21.

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
67%
15154
28%
46907
25%
15127
72%
15127
46%
23618

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
63%
716
21%
2506
21%
716
68%
716
32%
1382
January16th to endNight
65%
768
25%
2541
25%
768
69%
768
35%
1398
February1st to 15thNight
61%
697
22%
2232
23%
696
65%
696
36%
1229
February16th to endNight
59%
632
28%
1895
26%
632
65%
632
41%
1010
March1st to 15thNight
59%
720
21%
2127
18%
720
65%
720
42%
1140
March16th to endNight
56%
768
22%
2013
15%
768
62%
768
44%
1138
April1st to 15thNight
55%
719
24%
1799
12%
719
60%
719
41%
1063
April16th to endNight
60%
720
25%
1800
13%
720
64%
720
46%
1021
May1st to 15thNight
60%
537
28%
1617
21%
537
64%
537
49%
782
May16th to endNight
67%
374
24%
1496
26%
374
71%
374
37%
700
June1st to 15thNight
73%
360
27%
1440
34%
360
78%
360
42%
614
June16th to endNight
79%
360
33%
1440
43%
360
85%
360
63%
495
July1st to 15thNight
87%
340
32%
1360
43%
340
90%
340
63%
469
July16th to endNight
84%
397
39%
1436
46%
374
87%
374
60%
528
August1st to 15thNight
81%
610
34%
1683
25%
607
83%
607
64%
795
August16th to endNight
80%
764
44%
1910
27%
764
82%
764
76%
885
September1st to 15thNight
84%
720
41%
1800
27%
720
87%
720
75%
848
September16th to endNight
76%
680
43%
1842
35%
680
82%
680
67%
843
October1st to 15thNight
71%
660
33%
1957
30%
660
78%
660
52%
952
October16th to endNight
72%
704
35%
2148
34%
704
78%
704
54%
998
November1st to 15thNight
70%
700
28%
2275
28%
700
74%
700
44%
1137
November16th to endNight
63%
720
27%
2382
26%
720
69%
720
41%
1200
December1st to 15thNight
58%
720
20%
2520
18%
720
65%
720
30%
1428
December16th to endNight
52%
768
23%
2688
20%
768
59%
768
28%
1563

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
231332345%7%62%
47966
Night
231332345%8%61%
47082
TransparencyDay
21%410%22%22%19%
47640
Night
21%412%25%21%13%
46908
SeeingDay
7%12%26%28%17%6%
5755
Night
4417%41%26%5%
15167

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
1435%5%45%5%6%11%46%
1432
16th to endDay
35%25%5%46%6%8%9%43%
1680
February1st to 15thDay
2424435%5%6%12%48%
1631
16th to endDay
242443347%11%50%
1579
March1st to 15thDay
23245%35%5%6%10%49%
1832
16th to endDay
13145%45%5%6%8%54%
2209
April1st to 15thDay
23345%3446%8%51%
2149
16th to endDay
2423323446%62%
2160
May1st to 15thDay
3213323347%64%
2328
16th to endDay
44245%25%45%5%54%
2615
June1st to 15thDay
221332445%7%62%
2520
16th to endDay
11121222479%
2520
July1st to 15thDay
1113445%75%
2520
16th to endDay
11122233475%
2633
August1st to 15thDay
11221333474%
2265
16th to endDay
1111222382%
2292
September1st to 15thDay
1121123479%
2160
16th to endDay
212212335%75%
1910
October1st to 15thDay
2213312346%66%
1672
16th to endDay
233313447%65%
1724
November1st to 15thDay
33133145%5%7%59%
1584
16th to endDay
1324425%5%410%57%
1575
December1st to 15thDay
2434425%6%8%12%46%
1440
16th to endDay
26%26%6%36%6%8%11%39%
1536
January1st to 15thNight
1425%6%35%6%7%11%44%
2506
16th to endNight
24245%246%7%10%48%
2541
February1st to 15thNight
1423435%5%7%10%50%
2221
16th to endNight
242442346%10%55%
1895
March1st to 15thNight
23134145%7%11%54%
2127
16th to endNight
1323325%35%9%59%
2013
April1st to 15thNight
2214425%6%6%10%52%
1799
16th to endNight
3313224447%62%
1800
May1st to 15thNight
321222345%6%65%
1617
16th to endNight
231342446%8%57%
1496
June1st to 15thNight
3213213246%67%
1440
16th to endNight
11221112380%
1440
July1st to 15thNight
11112326%77%
1440
16th to endNight
11121132478%
1533
August1st to 15thNight
211121244473%
1692
16th to endNight
11121112482%
1910
September1st to 15thNight
11111123481%
1800
16th to endNight
1112212235%77%
1842
October1st to 15thNight
3212423335%67%
1957
16th to endNight
223212346%68%
2148
November1st to 15thNight
121331346%8%61%
2275
16th to endNight
132442335%7%59%
2382
December1st to 15thNight
2425%4345%6%10%50%
2520
16th to endNight
25%35%425%6%7%12%44%
2688

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
31%8%18%29%11%
1432
16th to endDay
33%9%14%24%14%3
1680
February1st to 15thDay
28%5%19%28%14%3
1631
16th to endDay
26%5%17%34%13%2
1579
March1st to 15thDay
27%6%21%25%16%2
1832
16th to endDay
26%8%21%26%13%4
2209
April1st to 15thDay
30%5%13%27%18%4
2149
16th to endDay
22%312%31%24%5%
2160
May1st to 15thDay
20%28%30%31%6%
2328
16th to endDay
29%39%24%25%7%
2619
June1st to 15thDay
22%37%20%27%18%
2520
16th to endDay
11%2113%31%39%
2520
July1st to 15thDay
10%328%21%54%
2371
16th to endDay
13%218%21%53%
2468
August1st to 15thDay
13%319%22%49%
2249
16th to endDay
9%117%31%49%
2292
September1st to 15thDay
10%1111%31%43%
2160
16th to endDay
12%3321%34%24%
1910
October1st to 15thDay
19%27%27%32%10%
1672
16th to endDay
19%210%30%26%10%
1724
November1st to 15thDay
23%5%16%30%18%6%
1584
16th to endDay
24%414%30%23%2
1575
December1st to 15thDay
30%8%16%31%12%1
1440
16th to endDay
37%8%16%24%11%
1536
January1st to 15thNight
30%6%17%30%13%1
2506
16th to endNight
29%5%15%26%17%4
2541
February1st to 15thNight
27%6%17%30%13%4
2232
16th to endNight
24%5%16%35%14%2
1895
March1st to 15thNight
23%5%21%27%15%4
2127
16th to endNight
22%6%22%29%15%3
2013
April1st to 15thNight
25%6%17%31%16%2
1799
16th to endNight
22%6%15%31%19%5%
1800
May1st to 15thNight
18%39%31%27%8%
1618
16th to endNight
24%413%29%22%6%
1496
June1st to 15thNight
20%48%22%26%18%
1440
16th to endNight
11%1415%32%35%
1440
July1st to 15thNight
10%128%27%50%
1360
16th to endNight
12%228%23%49%
1436
August1st to 15thNight
14%2213%24%42%
1683
16th to endNight
8%1110%36%41%
1910
September1st to 15thNight
9%1411%33%39%
1800
16th to endNight
11%1323%34%24%
1842
October1st to 15thNight
19%27%30%30%9%
1957
16th to endNight
17%39%30%31%7%
2148
November1st to 15thNight
20%7%14%33%17%6%
2275
16th to endNight
23%413%31%21%4
2382
December1st to 15thNight
29%9%16%29%13%1
2520
16th to endNight
31%9%16%26%14%1
2688

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
6%16%20%40%10%6%
60
16th to endDay
9%322%35%23%6%
208
February1st to 15thDay
10%8%19%36%19%4
246
16th to endDay
9%10%23%31%22%2
238
March1st to 15thDay
5%15%26%31%15%5%
270
16th to endDay
11%20%27%25%12%2
288
April1st to 15thDay
13%21%22%21%14%6%
269
16th to endDay
13%20%29%24%9%3
270
May1st to 15thDay
12%19%26%23%12%4
288
16th to endDay
12%14%23%24%16%9%
330
June1st to 15thDay
11%16%27%23%16%4
315
16th to endDay
413%28%26%18%8%
315
July1st to 15thDay
28%29%30%19%10%
305
16th to endDay
7%30%33%17%9%
327
August1st to 15thDay
310%31%29%14%10%
315
16th to endDay
28%30%27%18%12%
332
September1st to 15thDay
37%25%32%23%6%
315
16th to endDay
7%12%24%24%26%4
276
October1st to 15thDay
10%12%29%23%17%6%
255
16th to endDay
12%13%23%29%17%2
236
November1st to 15thDay
5%316%26%27%20%
90
16th to endDay
7%15%25%32%15%3
83
December1st to 15thDay
8%11%23%41%10%5%
60
16th to endDay
7%6%17%40%25%3
64
January1st to 15thNight
4416%41%25%7%
720
16th to endNight
5%314%44%25%6%
768
February1st to 15thNight
35%19%42%23%4
704
16th to endNight
5%6%21%41%20%5%
632
March1st to 15thNight
5%5%23%38%21%5%
720
16th to endNight
38%26%37%20%2
768
April1st to 15thNight
411%22%38%21%1
719
16th to endNight
5%9%21%35%23%4
720
May1st to 15thNight
5%7%21%39%22%3
538
16th to endNight
45%15%43%27%3
375
June1st to 15thNight
5%412%50%23%3
360
16th to endNight
2113%52%27%2
360
July1st to 15thNight
17%54%32%3
340
16th to endNight
27%49%36%3
397
August1st to 15thNight
210%45%36%4
610
16th to endNight
1113%44%34%4
764
September1st to 15thNight
1110%34%43%8%
720
16th to endNight
2313%34%32%13%
680
October1st to 15thNight
6%313%39%28%8%
660
16th to endNight
5%215%36%26%12%
704
November1st to 15thNight
4217%40%29%6%
700
16th to endNight
5%5%19%40%21%7%
720
December1st to 15thNight
5%422%41%19%6%
720
16th to endNight
6%5%25%40%18%3
768
Page generated at 2017-09-22 04:35:35. Version ac04

Copyright 2017 A. Danko


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