Greene
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Greene clear sky chart from 2005-11-05 to 2017-12-02.

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
28%
15105
17%
47986
8%
15073
39%
15073
19%
32006

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
21%
720
18%
2506
7%
716
36%
716
17%
1602
January16th to endNight
16%
768
17%
2688
4%
768
32%
768
14%
1778
February1st to 15thNight
17%
704
14%
2258
4%
701
29%
701
13%
1594
February16th to endNight
20%
631
19%
1893
6%
631
35%
631
17%
1303
March1st to 15thNight
18%
720
15%
2127
5%
720
29%
720
16%
1513
March16th to endNight
25%
768
21%
2073
6%
768
36%
768
22%
1378
April1st to 15thNight
20%
715
17%
1793
3%
715
29%
715
20%
1301
April16th to endNight
25%
540
16%
1620
6%
540
33%
540
18%
1118
May1st to 15thNight
27%
540
13%
1620
7%
540
34%
540
17%
1143
May16th to endNight
28%
413
11%
1535
9%
412
36%
412
14%
1105
June1st to 15thNight
30%
360
8%
1440
6%
360
38%
360
13%
1030
June16th to endNight
44%
360
9%
1440
10%
360
49%
360
19%
933
July1st to 15thNight
46%
340
9%
1360
13%
340
50%
340
20%
858
July16th to endNight
48%
376
11%
1418
11%
354
54%
354
21%
877
August1st to 15thNight
45%
509
13%
1580
9%
507
49%
507
23%
1040
August16th to endNight
46%
639
21%
1785
12%
639
50%
639
34%
1108
September1st to 15thNight
41%
720
18%
1887
8%
720
47%
720
33%
1210
September16th to endNight
44%
717
26%
1980
16%
717
53%
717
35%
1166
October1st to 15thNight
36%
720
20%
2034
10%
720
45%
720
26%
1320
October16th to endNight
21%
768
16%
2488
6%
768
34%
768
18%
1651
November1st to 15thNight
31%
760
20%
2472
11%
760
43%
760
20%
1593
November16th to endNight
26%
783
21%
2546
9%
783
40%
783
19%
1640
December1st to 15thNight
19%
759
15%
2714
4%
759
33%
759
15%
1855
December16th to endNight
18%
775
17%
2729
5%
775
34%
775
14%
1890

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
18%6%25%42445%6%38%
48462
Night
18%7%24424446%38%
48156
TransparencyDay
45%5%11%21%13%1
48150
Night
45%5%11%22%13%1
47986
SeeingDay
22%14%30%20%9%3
6125
Night
22%12%31%25%8%
15105

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
17%5%434245%46%39%
1432
16th to endDay
15%9%25%32445%5%39%
1536
February1st to 15thDay
16%9%26%6%35%5%45%34%
1603
16th to endDay
14%9%46%5%25%5%5%5%35%
1580
March1st to 15thDay
18%9%35%5%3435%6%34%
1823
16th to endDay
15%7%35%5%23345%42%
2148
April1st to 15thDay
19%7%25%424446%37%
2155
16th to endDay
20%5%245%24446%39%
2340
May1st to 15thDay
26%7%35%424446%30%
2332
16th to endDay
21%5%35%5%245%5%6%34%
2590
June1st to 15thDay
25%7%35%424447%29%
2520
16th to endDay
21%6%245%45%5%5%6%32%
2520
July1st to 15thDay
13%5%25%5%36%6%6%8%35%
2520
16th to endDay
13%5%25%5%46%5%7%9%34%
2654
August1st to 15thDay
15%5%25%435%5%6%8%37%
2355
16th to endDay
12%42442346%7%46%
2415
September1st to 15thDay
15%5%24433246%47%
2073
16th to endDay
13%413313347%52%
1980
October1st to 15thDay
18%6%25%5%23336%41%
1926
16th to endDay
20%6%25%424336%41%
1734
November1st to 15thDay
20%6%1431435%6%40%
1716
16th to endDay
22%5%2431325%5%43%
1739
December1st to 15thDay
23%8%335%2334436%
1280
16th to endDay
22%12%35%42333433%
1491
January1st to 15thNight
16%8%24324447%40%
2506
16th to endNight
15%9%26%5%2445%5%37%
2688
February1st to 15thNight
13%8%46%7%46%5%45%33%
2257
16th to endNight
16%9%345%35%345%38%
1893
March1st to 15thNight
18%10%35%434445%34%
2114
16th to endNight
17%5%35%324445%43%
2073
April1st to 15thNight
20%7%34435%44436%
1793
16th to endNight
23%5%25%434445%36%
1620
May1st to 15thNight
20%8%345%3445%7%33%
1620
16th to endNight
21%8%46%5%3445%6%28%
1533
June1st to 15thNight
25%7%26%425%347%29%
1440
16th to endNight
19%6%3432346%8%35%
1440
July1st to 15thNight
14%425%5%45%5%5%7%37%
1440
16th to endNight
14%424425%5%5%8%39%
1514
August1st to 15thNight
14%425%5%446%5%8%38%
1590
16th to endNight
13%32432345%9%46%
1785
September1st to 15thNight
15%6%13423346%49%
1887
16th to endNight
13%41332235%6%52%
1980
October1st to 15thNight
18%5%2433345%5%43%
2034
16th to endNight
23%5%2442335%6%38%
2488
November1st to 15thNight
18%6%23334346%42%
2472
16th to endNight
17%6%24434345%42%
2546
December1st to 15thNight
23%9%25%413345%35%
2714
16th to endNight
22%9%34424435%35%
2729

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
44%6%11%22%13%1
1433
16th to endDay
43%6%12%23%12%1
1536
February1st to 15thDay
51%411%19%11%
1606
16th to endDay
49%5%10%18%13%2
1580
March1st to 15thDay
51%311%18%12%2
1833
16th to endDay
44%48%19%18%4
2148
April1st to 15thDay
48%48%19%16%3
2155
16th to endDay
45%6%10%19%14%4
2340
May1st to 15thDay
53%5%7%17%14%2
2332
16th to endDay
48%6%12%18%12%1
2594
June1st to 15thDay
54%6%10%18%9%
2520
16th to endDay
50%6%9%19%11%
2520
July1st to 15thDay
41%8%14%24%10%
2371
16th to endDay
44%7%15%21%10%
2487
August1st to 15thDay
43%6%15%25%9%
2341
16th to endDay
33%6%14%26%17%1
2415
September1st to 15thDay
37%5%10%26%18%1
2073
16th to endDay
31%410%30%22%1
1980
October1st to 15thDay
44%49%25%14%1
1926
16th to endDay
44%411%25%12%
1734
November1st to 15thDay
44%5%13%22%14%1
1716
16th to endDay
42%415%19%15%1
1739
December1st to 15thDay
50%412%20%11%
1280
16th to endDay
55%49%16%12%1
1491
January1st to 15thNight
43%5%12%24%11%1
2506
16th to endNight
47%5%9%20%14%2
2688
February1st to 15thNight
51%5%11%19%11%1
2258
16th to endNight
48%49%21%13%2
1893
March1st to 15thNight
51%49%19%12%2
2127
16th to endNight
41%5%9%19%18%5%
2073
April1st to 15thNight
49%47%18%16%2
1793
16th to endNight
48%5%9%20%12%3
1620
May1st to 15thNight
49%6%9%17%13%2
1620
16th to endNight
54%6%11%16%10%1
1535
June1st to 15thNight
54%6%10%17%7%1
1440
16th to endNight
44%6%14%20%12%
1440
July1st to 15thNight
43%6%16%22%11%
1360
16th to endNight
40%7%17%22%10%
1418
August1st to 15thNight
41%8%14%24%10%
1580
16th to endNight
33%6%14%28%15%
1785
September1st to 15thNight
36%5%11%29%15%1
1887
16th to endNight
31%411%33%17%1
1980
October1st to 15thNight
40%5%11%25%15%1
2034
16th to endNight
47%412%23%11%1
2488
November1st to 15thNight
43%5%12%23%14%1
2472
16th to endNight
43%412%22%14%1
2546
December1st to 15thNight
50%410%22%11%
2714
16th to endNight
51%5%10%19%12%
2729

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
15%25%36%15%8%
60
16th to endDay
21%28%26%20%3
64
February1st to 15thDay
26%16%34%16%5%
219
16th to endDay
18%20%34%20%5%
239
March1st to 15thDay
28%22%28%15%4
270
16th to endDay
20%26%30%14%5%2
288
April1st to 15thDay
28%15%31%15%6%2
270
16th to endDay
23%17%31%16%7%4
270
May1st to 15thDay
36%15%20%17%7%1
288
16th to endDay
25%12%33%21%5%
331
June1st to 15thDay
23%16%31%19%8%
315
16th to endDay
21%10%37%19%9%2
315
July1st to 15thDay
15%7%38%23%11%3
305
16th to endDay
14%6%35%26%13%3
326
August1st to 15thDay
16%9%24%30%14%3
313
16th to endDay
14%9%21%30%15%8%
332
September1st to 15thDay
19%7%28%20%18%5%
315
16th to endDay
15%10%28%17%14%12%
314
October1st to 15thDay
21%13%25%19%15%4
301
16th to endDay
26%15%30%18%9%
288
November1st to 15thDay
26%13%28%19%9%2
280
16th to endDay
27%15%27%20%7%1
285
December1st to 15thDay
26%13%38%13%8%
73
16th to endDay
37%21%28%12%
64
January1st to 15thNight
21%17%33%23%3
720
16th to endNight
22%18%35%19%2
768
February1st to 15thNight
19%17%37%22%2
704
16th to endNight
23%15%34%21%5%
631
March1st to 15thNight
25%17%35%18%2
720
16th to endNight
20%18%32%22%5%
768
April1st to 15thNight
24%16%35%19%4
715
16th to endNight
24%15%30%22%5%
540
May1st to 15thNight
25%10%30%25%7%
540
16th to endNight
26%7%28%30%5%
413
June1st to 15thNight
29%6%27%28%8%
360
16th to endNight
21%325%37%11%
360
July1st to 15thNight
17%125%36%18%
340
16th to endNight
15%225%37%18%
376
August1st to 15thNight
15%326%38%16%
509
16th to endNight
13%427%33%18%2
639
September1st to 15thNight
16%5%29%31%14%1
720
16th to endNight
16%6%28%26%19%2
717
October1st to 15thNight
21%9%27%26%13%1
720
16th to endNight
26%13%33%20%6%
768
November1st to 15thNight
22%11%31%25%8%1
760
16th to endNight
21%15%30%23%7%1
783
December1st to 15thNight
27%13%34%19%4
759
16th to endNight
30%15%31%20%2
775
Page generated at 2017-12-03 11:16:47. Version ac04

Copyright 2017 A. Danko


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