Cherry Hill Farm
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cherry Hill Farm clear sky chart from 2005-11-05 to 2017-10-31.

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
44%
15854
22%
47423
13%
15813
52%
15813
24%
29838

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
26%
719
24%
2327
11%
716
43%
716
22%
1372
January16th to endNight
29%
768
25%
2496
13%
768
46%
768
24%
1484
February1st to 15thNight
28%
703
25%
2196
11%
701
44%
701
25%
1274
February16th to endNight
25%
631
26%
1893
9%
631
41%
631
24%
1169
March1st to 15thNight
33%
720
26%
1990
15%
720
43%
720
26%
1251
March16th to endNight
32%
768
19%
2112
8%
768
40%
768
24%
1382
April1st to 15thNight
38%
718
23%
1958
12%
718
46%
718
29%
1179
April16th to endNight
43%
573
23%
1653
12%
573
51%
573
26%
1032
May1st to 15thNight
42%
540
16%
1620
9%
540
47%
540
21%
1079
May16th to endNight
48%
561
16%
1684
9%
561
52%
561
20%
1094
June1st to 15thNight
57%
540
12%
1620
8%
540
60%
540
21%
1103
June16th to endNight
60%
540
15%
1620
10%
540
63%
540
25%
1063
July1st to 15thNight
62%
510
10%
1530
8%
510
62%
510
22%
1040
July16th to endNight
62%
564
12%
1595
9%
531
68%
531
23%
1071
August1st to 15thNight
61%
539
12%
1609
11%
536
62%
536
21%
1134
August16th to endNight
62%
627
16%
1823
14%
627
64%
627
21%
1277
September1st to 15thNight
58%
720
17%
1980
15%
720
59%
720
26%
1354
September16th to endNight
51%
717
20%
1980
15%
717
56%
717
24%
1333
October1st to 15thNight
49%
720
29%
2076
24%
720
57%
720
30%
1268
October16th to endNight
52%
768
35%
2303
26%
768
66%
768
37%
1271
November1st to 15thNight
47%
700
28%
2182
22%
700
57%
700
32%
1214
November16th to endNight
38%
720
27%
2340
17%
720
52%
720
26%
1344
December1st to 15thNight
36%
720
24%
2340
14%
720
50%
720
21%
1428
December16th to endNight
29%
768
23%
2496
11%
768
43%
768
18%
1622

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
13%4244245%6%7%43%
48323
Night
14%42442445%7%45%
47620
TransparencyDay
37%7%13%19%16%4
48024
Night
37%6%12%19%19%5%
47423
SeeingDay
15%11%15%21%21%13%
5705
Night
14%18%17%26%20%3
15858

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
17%5%13423335%48%
1611
16th to endDay
15%323323346%50%
1728
February1st to 15thDay
14%423324346%48%
1663
16th to endDay
13%424324346%49%
1580
March1st to 15thDay
16%31332435%7%48%
1968
16th to endDay
18%413324447%44%
2111
April1st to 15thDay
13%322324447%49%
1990
16th to endDay
14%324335%45%6%45%
2316
May1st to 15thDay
12%5%145%35%5%6%8%41%
2331
16th to endDay
11%5%14435%5%6%10%39%
2431
June1st to 15thDay
9%425%6%36%6%8%10%34%
2340
16th to endDay
6%3245%36%8%9%10%39%
2340
July1st to 15thDay
10%426%5%47%6%7%10%32%
2340
16th to endDay
7%315%6%47%8%9%10%34%
2465
August1st to 15thDay
13%6%35%6%46%7%7%9%29%
2340
16th to endDay
12%5%25%7%35%5%7%11%32%
2364
September1st to 15thDay
11%416%5%345%6%8%41%
1980
16th to endDay
18%4244245%47%41%
1980
October1st to 15thDay
17%413212235%56%
1884
16th to endDay
11%41331222362%
1920
November1st to 15thDay
12%31221334459%
1673
16th to endDay
17%422323246%51%
1620
December1st to 15thDay
15%42423346%5%45%
1620
16th to endDay
22%5%23313345%43%
1728
January1st to 15thNight
16%423313345%51%
2327
16th to endNight
16%5%23324446%48%
2496
February1st to 15thNight
14%413323445%52%
2187
16th to endNight
13%3245%25%445%48%
1893
March1st to 15thNight
14%5%13314346%48%
1990
16th to endNight
16%4235%24346%45%
2112
April1st to 15thNight
13%41331335%7%50%
1958
16th to endNight
13%3245%2345%6%48%
1653
May1st to 15thNight
14%426%6%445%47%41%
1619
16th to endNight
10%425%6%35%5%5%9%41%
1682
June1st to 15thNight
10%425%5%36%7%7%12%33%
1620
16th to endNight
9%325%437%6%7%10%40%
1620
July1st to 15thNight
9%425%5%38%6%8%10%33%
1620
16th to endNight
6%325%5%37%6%9%13%33%
1703
August1st to 15thNight
13%5%25%5%35%6%8%11%33%
1620
16th to endNight
12%5%25%446%6%7%10%34%
1823
September1st to 15thNight
12%5%25%6%35%5%5%8%38%
1980
16th to endNight
18%5%245%3435%6%41%
1980
October1st to 15thNight
17%41331223453%
2076
16th to endNight
11%31322333460%
2303
November1st to 15thNight
12%313323235%57%
2182
16th to endNight
17%412313346%51%
2340
December1st to 15thNight
16%5%14323346%47%
2340
16th to endNight
22%424413346%40%
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
37%5%9%20%21%4
1612
16th to endDay
35%37%23%21%8%
1728
February1st to 15thDay
35%49%21%23%5%
1665
16th to endDay
35%5%11%23%18%5%
1580
March1st to 15thDay
36%5%8%23%20%6%
1968
16th to endDay
39%7%13%20%17%2
2112
April1st to 15thDay
32%5%11%23%21%5%
1990
16th to endDay
37%7%10%19%17%7%
2316
May1st to 15thDay
39%8%15%19%14%2
2331
16th to endDay
37%9%17%20%12%2
2435
June1st to 15thDay
39%11%19%20%7%
2340
16th to endDay
33%12%19%18%13%2
2340
July1st to 15thDay
41%12%18%15%9%3
2201
16th to endDay
36%14%20%17%8%1
2310
August1st to 15thDay
46%12%15%16%7%1
2327
16th to endDay
42%11%17%18%8%1
2364
September1st to 15thDay
39%10%13%18%14%4
1980
16th to endDay
41%7%12%17%18%3
1980
October1st to 15thDay
32%310%22%24%6%
1884
16th to endDay
28%35%21%28%10%
1920
November1st to 15thDay
28%39%19%28%9%
1673
16th to endDay
35%47%22%23%7%
1620
December1st to 15thDay
38%5%10%20%18%6%
1620
16th to endDay
42%410%18%17%6%
1728
January1st to 15thNight
35%5%10%17%24%6%
2327
16th to endNight
37%47%20%23%6%
2496
February1st to 15thNight
33%49%21%24%5%
2196
16th to endNight
36%5%10%21%23%3
1893
March1st to 15thNight
35%5%9%20%21%7%
1990
16th to endNight
39%5%12%20%17%4
2112
April1st to 15thNight
32%410%25%21%5%
1958
16th to endNight
35%5%11%18%20%7%
1653
May1st to 15thNight
42%6%12%19%15%2
1620
16th to endNight
37%9%13%25%11%2
1684
June1st to 15thNight
39%12%20%20%7%1
1620
16th to endNight
35%11%19%17%13%3
1620
July1st to 15thNight
39%11%20%16%8%2
1530
16th to endNight
34%15%22%17%7%2
1595
August1st to 15thNight
41%12%20%13%11%1
1609
16th to endNight
40%12%18%18%8%
1823
September1st to 15thNight
41%8%15%18%13%3
1980
16th to endNight
42%6%12%16%17%4
1980
October1st to 15thNight
35%48%22%23%5%
2076
16th to endNight
28%35%21%29%11%
2303
November1st to 15thNight
31%37%17%28%11%
2182
16th to endNight
34%46%20%26%7%
2340
December1st to 15thNight
38%5%10%19%19%7%
2340
16th to endNight
44%5%9%16%18%5%
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
18%16%35%20%8%
90
16th to endDay
14%17%45%16%5%
96
February1st to 15thDay
17%16%44%20%1
90
16th to endDay
17%12%43%18%8%
81
March1st to 15thDay
17%22%24%27%7%
258
16th to endDay
19%19%22%24%11%1
288
April1st to 15thDay
13%21%17%24%19%2
270
16th to endDay
18%13%17%23%17%10%
270
May1st to 15thDay
12%17%24%20%17%7%
288
16th to endDay
15%12%11%21%25%14%
331
June1st to 15thDay
11%11%10%18%24%22%
315
16th to endDay
9%10%12%24%20%22%
315
July1st to 15thDay
9%7%8%20%27%26%
305
16th to endDay
5%10%5%16%32%30%
326
August1st to 15thDay
20%6%7%20%22%22%
313
16th to endDay
14%5%6%16%29%27%
332
September1st to 15thDay
14%6%10%15%30%22%
315
16th to endDay
21%7%9%19%27%15%
314
October1st to 15thDay
22%6%12%26%24%7%
315
16th to endDay
13%10%12%33%22%7%
336
November1st to 15thDay
22%13%19%19%18%6%
181
16th to endDay
17%6%24%31%17%2
90
December1st to 15thDay
17%11%38%22%10%
90
16th to endDay
31%17%27%18%5%
96
January1st to 15thNight
16%25%26%25%5%
720
16th to endNight
14%23%28%30%2
768
February1st to 15thNight
13%24%29%29%2
704
16th to endNight
11%24%32%27%3
631
March1st to 15thNight
17%22%23%29%6%
720
16th to endNight
17%20%24%26%10%
768
April1st to 15thNight
14%23%21%27%12%
718
16th to endNight
13%20%17%28%18%1
573
May1st to 15thNight
14%19%17%29%18%
540
16th to endNight
13%18%9%23%30%4
563
June1st to 15thNight
9%17%7%23%32%9%
540
16th to endNight
7%16%7%21%36%10%
540
July1st to 15thNight
11%12%421%41%9%
510
16th to endNight
5%16%5%17%42%12%
564
August1st to 15thNight
15%9%423%40%7%
539
16th to endNight
13%9%322%41%9%
627
September1st to 15thNight
12%8%7%22%38%9%
720
16th to endNight
18%9%10%24%31%5%
717
October1st to 15thNight
19%10%15%22%27%4
720
16th to endNight
11%11%19%31%22%2
768
November1st to 15thNight
12%18%18%31%16%3
700
16th to endNight
15%22%20%25%15%
720
December1st to 15thNight
17%21%19%31%8%
720
16th to endNight
22%21%23%27%5%
768
Page generated at 2017-11-01 17:23:30. Version ac04

Copyright 2017 A. Danko


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