Anna Maria College
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Anna Maria College clear sky chart from 2005-11-06 to 2024-11-04.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	17% 8% 3 6% 4 4 4 4 5% 7% 37%	101242
	Night	17% 8% 3 6% 4 4 4 3 5% 6% 39%	97787
Transparency	Day	44% 6% 12% 22% 14% 2	104793
	Night	43% 6% 12% 22% 15% 2	102325
Seeing	Day	23% 17% 32% 19% 7% 2	15006
	Night	22% 17% 34% 21% 6%	23930

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	13% 8% 3 7% 4 3 4 3 4 5% 44%	2517
	11th to 20th	Day	16% 8% 4 8% 5% 4 5% 3 5% 5% 37%	2520
	21st to end	Day	20% 12% 3 6% 5% 4 4 4 4 5% 33%	2772
February	1st to 10th	Day	17% 8% 3 6% 5% 5% 5% 5% 6% 6% 35%	1771
	11th to 20th	Day	12% 8% 2 7% 5% 6% 5% 4 6% 6% 39%	1848
	21st to end	Day	19% 10% 4 7% 4 4 4 2 4 5% 37%	1570
March	1st to 10th	Day	22% 15% 4 7% 4 4 3 3 4 4 31%	3116
	11th to 20th	Day	12% 7% 2 6% 4 5% 5% 5% 7% 8% 39%	3288
	21st to end	Day	20% 9% 3 5% 4 4 4 3 6% 7% 34%	4092
April	1st to 10th	Day	17% 10% 3 6% 6% 4 3 3 5% 6% 36%	2280
	11th to 20th	Day	18% 7% 2 6% 4 4 4 4 5% 7% 39%	2254
	21st to end	Day	21% 7% 3 7% 4 5% 4 4 4 7% 35%	2453
May	1st to 10th	Day	24% 11% 3 8% 4 4 4 3 5% 7% 27%	4106
	11th to 20th	Day	22% 9% 3 8% 4 4 4 3 5% 6% 33%	4225
	21st to end	Day	14% 5% 2 5% 4 4 4 4 6% 8% 43%	4837
June	1st to 10th	Day	18% 6% 2 6% 4 5% 5% 4 7% 8% 35%	2660
	11th to 20th	Day	16% 6% 3 6% 5% 4 4 4 7% 8% 36%	2660
	21st to end	Day	18% 7% 2 7% 5% 5% 4 4 6% 8% 33%	2660
July	1st to 10th	Day	12% 7% 2 6% 5% 6% 5% 5% 7% 9% 35%	4440
	11th to 20th	Day	12% 6% 2 6% 4 5% 5% 4 7% 10% 38%	4440
	21st to end	Day	18% 9% 3 6% 4 4 4 4 6% 7% 34%	4814
August	1st to 10th	Day	16% 7% 2 7% 5% 5% 5% 5% 7% 8% 32%	4209
	11th to 20th	Day	12% 6% 3 7% 5% 5% 6% 4 6% 7% 38%	3919
	21st to end	Day	8% 4 2 7% 4 5% 5% 4 6% 10% 45%	4180
September	1st to 10th	Day	13% 6% 3 5% 5% 4 4 4 6% 6% 44%	2280
	11th to 20th	Day	15% 6% 2 4 2 3 3 4 5% 6% 50%	2110
	21st to end	Day	17% 6% 3 5% 4 4 4 3 5% 7% 43%	2090
October	1st to 10th	Day	21% 7% 2 6% 3 4 4 3 4 5% 39%	2090
	11th to 20th	Day	14% 7% 2 5% 4 4 3 3 5% 7% 46%	1848
	21st to end	Day	20% 7% 3 6% 4 3 4 4 4 5% 40%	1881
November	1st to 10th	Day	14% 8% 3 6% 3 3 3 3 4 4 48%	1698
	11th to 20th	Day	19% 8% 2 4 3 3 3 3 5% 6% 45%	1710
	21st to end	Day	16% 9% 3 5% 4 4 4 4 5% 5% 42%	1706
December	1st to 10th	Day	17% 9% 3 6% 5% 5% 4 3 4 6% 36%	1520
	11th to 20th	Day	21% 7% 2 5% 3 3 3 2 5% 6% 43%	1906
	21st to end	Day	20% 12% 4 6% 4 4 4 4 5% 6% 31%	2772
January	1st to 10th	Night	17% 7% 2 5% 4 3 3 3 5% 6% 45%	4429
	11th to 20th	Night	15% 9% 3 8% 5% 4 3 3 5% 6% 39%	4440
	21st to end	Night	21% 13% 4 8% 4 3 4 3 5% 5% 30%	4884
February	1st to 10th	Night	15% 10% 2 6% 4 4 5% 4 5% 6% 39%	2405
	11th to 20th	Night	13% 9% 3 7% 5% 4 4 4 6% 6% 40%	2218
	21st to end	Night	17% 10% 3 6% 5% 4 3 3 5% 5% 39%	1884
March	1st to 10th	Night	25% 13% 2 5% 3 4 3 3 5% 5% 32%	3724
	11th to 20th	Night	12% 8% 3 6% 4 5% 5% 3 6% 8% 40%	3671
	21st to end	Night	22% 10% 3 6% 4 4 4 4 6% 6% 34%	3535
April	1st to 10th	Night	17% 9% 3 7% 5% 5% 4 4 5% 6% 35%	1900
	11th to 20th	Night	19% 8% 2 6% 4 4 4 3 5% 6% 39%	1875
	21st to end	Night	20% 7% 3 7% 4 3 4 3 4 6% 40%	1725
May	1st to 10th	Night	25% 9% 3 8% 5% 5% 4 3 5% 7% 27%	2834
	11th to 20th	Night	19% 10% 3 8% 6% 6% 5% 4 5% 6% 28%	2698
	21st to end	Night	16% 6% 2 6% 3 4 4 3 5% 8% 41%	2738
June	1st to 10th	Night	17% 7% 3 7% 6% 5% 3 3 6% 6% 37%	1520
	11th to 20th	Night	18% 8% 3 7% 3 5% 4 3 6% 7% 37%	1520
	21st to end	Night	15% 6% 2 6% 4 4 4 4 7% 8% 41%	1520
July	1st to 10th	Night	13% 7% 3 7% 6% 5% 5% 5% 7% 9% 35%	2520
	11th to 20th	Night	15% 8% 2 6% 4 4 4 4 6% 8% 39%	2520
	21st to end	Night	16% 9% 3 7% 5% 4 4 4 5% 6% 37%	2739
August	1st to 10th	Night	21% 6% 3 8% 5% 5% 6% 3 5% 6% 31%	2688
	11th to 20th	Night	13% 8% 3 8% 6% 5% 5% 4 5% 7% 37%	2904
	21st to end	Night	9% 4 2 5% 3 3 3 3 5% 7% 58%	3476
September	1st to 10th	Night	13% 6% 2 7% 3 4 3 4 5% 6% 46%	1900
	11th to 20th	Night	12% 7% 2 5% 4 3 4 2 4 6% 52%	2069
	21st to end	Night	17% 7% 3 6% 3 3 4 3 5% 6% 44%	2090
October	1st to 10th	Night	20% 7% 2 5% 3 4 3 3 5% 6% 41%	2090
	11th to 20th	Night	15% 6% 2 5% 3 4 4 3 4 7% 47%	2328
	21st to end	Night	21% 8% 2 6% 4 4 3 3 4 6% 39%	2717
November	1st to 10th	Night	14% 7% 2 4 4 4 4 3 5% 5% 48%	2453
	11th to 20th	Night	17% 7% 2 5% 4 4 4 4 4 6% 44%	2470
	21st to end	Night	15% 7% 2 5% 4 4 4 4 5% 6% 43%	2471
December	1st to 10th	Night	17% 11% 2 7% 4 4 3 3 4 6% 38%	2660
	11th to 20th	Night	19% 7% 2 5% 4 4 4 4 6% 6% 39%	3288
	21st to end	Night	20% 11% 4 7% 4 4 4 3 5% 6% 33%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	40% 5% 10% 34% 10% 2	2518
	11th to 20th	Day	47% 6% 10% 25% 11% 1	2520
	21st to end	Day	53% 5% 9% 21% 10% 2	2772
February	1st to 10th	Day	47% 6% 13% 20% 12% 2	1771
	11th to 20th	Day	44% 6% 10% 22% 15% 3	1857
	21st to end	Day	50% 4 10% 20% 14% 2	1570
March	1st to 10th	Day	56% 4 12% 14% 11% 2	3119
	11th to 20th	Day	37% 8% 17% 25% 11% 3	3288
	21st to end	Day	48% 4 6% 17% 19% 5%	4092
April	1st to 10th	Day	48% 4 10% 20% 14% 3	2280
	11th to 20th	Day	43% 5% 12% 20% 17% 3	2254
	21st to end	Day	48% 6% 9% 18% 17% 3	2453
May	1st to 10th	Day	55% 8% 12% 13% 11% 1	4120
	11th to 20th	Day	51% 6% 14% 18% 10% 1	4229
	21st to end	Day	36% 7% 12% 26% 18% 2	4837
June	1st to 10th	Day	46% 7% 12% 24% 11% 1	2660
	11th to 20th	Day	42% 8% 13% 21% 14% 2	2660
	21st to end	Day	46% 8% 12% 20% 13% 1	2660
July	1st to 10th	Day	44% 8% 11% 21% 14% 1	4370
	11th to 20th	Day	39% 7% 16% 25% 12% 1	4365
	21st to end	Day	48% 5% 13% 19% 13% 2	4661
August	1st to 10th	Day	48% 8% 15% 21% 8% 1	4195
	11th to 20th	Day	42% 7% 15% 26% 9% 1	3958
	21st to end	Day	34% 6% 11% 31% 17% 1	4180
September	1st to 10th	Day	39% 6% 11% 23% 19% 2	2280
	11th to 20th	Day	34% 4 9% 27% 23% 3	2110
	21st to end	Day	41% 5% 9% 23% 20% 2	2090
October	1st to 10th	Day	40% 5% 9% 23% 20% 3	3480
	11th to 20th	Day	32% 3 9% 27% 25% 4	3051
	21st to end	Day	34% 4 13% 28% 18% 3	3081
November	1st to 10th	Day	40% 4 12% 25% 17% 3	1698
	11th to 20th	Day	40% 5% 11% 22% 20% 2	1710
	21st to end	Day	42% 6% 13% 25% 12% 2	1706
December	1st to 10th	Day	48% 4 15% 17% 15% 2	1520
	11th to 20th	Day	43% 3 14% 20% 17% 2	1906
	21st to end	Day	52% 6% 11% 20% 11% 1	2772
January	1st to 10th	Night	39% 5% 12% 30% 12% 3	4429
	11th to 20th	Night	46% 5% 12% 23% 12% 2	4440
	21st to end	Night	56% 5% 10% 17% 11% 2	4884
February	1st to 10th	Night	45% 6% 13% 21% 12% 2	2405
	11th to 20th	Night	44% 5% 10% 21% 16% 4	2220
	21st to end	Night	46% 4 10% 23% 13% 4	1884
March	1st to 10th	Night	53% 6% 8% 20% 11% 2	3734
	11th to 20th	Night	40% 8% 15% 21% 15% 2	3672
	21st to end	Night	49% 4 8% 13% 20% 7%	3535
April	1st to 10th	Night	48% 5% 10% 19% 15% 3	1900
	11th to 20th	Night	45% 6% 10% 19% 18% 1	1875
	21st to end	Night	46% 5% 9% 20% 15% 5%	1725
May	1st to 10th	Night	54% 10% 12% 15% 8% 1	2840
	11th to 20th	Night	55% 8% 13% 14% 8% 2	2699
	21st to end	Night	40% 8% 14% 23% 15% 1	2739
June	1st to 10th	Night	46% 7% 10% 23% 12% 1	1520
	11th to 20th	Night	45% 7% 13% 22% 12% 1	1520
	21st to end	Night	39% 8% 15% 23% 14% 1	1520
July	1st to 10th	Night	43% 8% 14% 21% 14% 1	2480
	11th to 20th	Night	42% 7% 15% 23% 12%	2472
	21st to end	Night	47% 6% 12% 18% 16% 1	2651
August	1st to 10th	Night	52% 8% 12% 19% 9% 1	2678
	11th to 20th	Night	45% 8% 13% 25% 9%	2931
	21st to end	Night	26% 5% 16% 31% 20% 1	3476
September	1st to 10th	Night	39% 6% 11% 24% 19% 1	1900
	11th to 20th	Night	34% 5% 10% 24% 25% 2	2069
	21st to end	Night	41% 5% 8% 25% 18% 3	2090
October	1st to 10th	Night	38% 5% 14% 24% 16% 2	3480
	11th to 20th	Night	27% 4 12% 25% 28% 4	3864
	21st to end	Night	34% 4 12% 32% 16% 2	4467
November	1st to 10th	Night	37% 6% 11% 22% 20% 4	2453
	11th to 20th	Night	42% 4 11% 21% 19% 3	2470
	21st to end	Night	39% 6% 15% 26% 13% 1	2471
December	1st to 10th	Night	46% 5% 13% 23% 13% 1	2660
	11th to 20th	Night	43% 5% 15% 19% 16% 2	3288
	21st to end	Night	49% 6% 10% 24% 11% 1	4884

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	24% 28% 29% 15% 3	180
	11th to 20th	Day	30% 30% 30% 7% 3	180
	21st to end	Day	23% 27% 35% 12% 4	198
February	1st to 10th	Day	32% 23% 32% 12% 1	351
	11th to 20th	Day	27% 30% 34% 9% 1	456
	21st to end	Day	33% 18% 36% 11% 3 1	382
March	1st to 10th	Day	31% 21% 34% 12% 2	460
	11th to 20th	Day	29% 26% 29% 12% 3 1	460
	21st to end	Day	29% 22% 33% 10% 5% 2	506
April	1st to 10th	Day	32% 23% 29% 10% 5% 1	460
	11th to 20th	Day	30% 18% 36% 11% 4	452
	21st to end	Day	31% 18% 32% 14% 3 2	460
May	1st to 10th	Day	33% 20% 28% 14% 5% 1	463
	11th to 20th	Day	23% 17% 38% 17% 5% 1	487
	21st to end	Day	20% 12% 37% 20% 9% 2	529
June	1st to 10th	Day	18% 11% 38% 22% 9% 2	490
	11th to 20th	Day	17% 14% 37% 24% 7% 2	490
	21st to end	Day	18% 14% 36% 20% 9% 2	490
July	1st to 10th	Day	18% 8% 32% 28% 11% 3	485
	11th to 20th	Day	15% 7% 31% 34% 11% 3	484
	21st to end	Day	13% 10% 37% 30% 8% 1	532
August	1st to 10th	Day	12% 9% 32% 35% 11% 2	486
	11th to 20th	Day	16% 7% 32% 29% 12% 3	479
	21st to end	Day	12% 12% 31% 27% 14% 3	539
September	1st to 10th	Day	18% 10% 29% 23% 14% 5%	490
	11th to 20th	Day	21% 9% 28% 19% 14% 9%	490
	21st to end	Day	22% 12% 32% 21% 9% 4	490
October	1st to 10th	Day	28% 13% 27% 19% 11% 3	490
	11th to 20th	Day	20% 20% 30% 22% 6% 2	450
	21st to end	Day	28% 16% 32% 17% 6% 1	429
November	1st to 10th	Day	23% 18% 33% 18% 7% 1	374
	11th to 20th	Day	28% 22% 28% 17% 3 1	370
	21st to end	Day	26% 23% 31% 16% 5%	366
December	1st to 10th	Day	24% 31% 28% 14% 3	180
	11th to 20th	Day	36% 23% 34% 5% 2	180
	21st to end	Day	29% 26% 33% 7% 4 1	198
January	1st to 10th	Night	23% 23% 39% 14% 1	760
	11th to 20th	Night	29% 22% 33% 14% 2	760
	21st to end	Night	22% 23% 35% 17% 2	836
February	1st to 10th	Night	24% 21% 37% 16% 1	760
	11th to 20th	Night	22% 27% 39% 11% 1	743
	21st to end	Night	27% 23% 34% 14% 2	628
March	1st to 10th	Night	25% 22% 35% 16% 2	760
	11th to 20th	Night	22% 25% 35% 16% 2	760
	21st to end	Night	26% 22% 31% 19% 3	836
April	1st to 10th	Night	25% 19% 37% 16% 3	760
	11th to 20th	Night	24% 21% 33% 18% 4	751
	21st to end	Night	24% 22% 34% 17% 3	585
May	1st to 10th	Night	30% 17% 31% 19% 3	570
	11th to 20th	Night	20% 18% 40% 18% 4	499
	21st to end	Night	21% 9% 37% 28% 5%	411
June	1st to 10th	Night	18% 9% 37% 29% 7%	380
	11th to 20th	Night	20% 8% 39% 26% 6%	380
	21st to end	Night	15% 6% 41% 32% 6%	380
July	1st to 10th	Night	15% 7% 33% 37% 8% 1	370
	11th to 20th	Night	17% 4 29% 37% 13% 1	368
	21st to end	Night	12% 6% 35% 38% 9%	416
August	1st to 10th	Night	12% 4 38% 36% 10%	482
	11th to 20th	Night	15% 6% 31% 33% 13% 1	632
	21st to end	Night	15% 6% 26% 37% 15% 2	836
September	1st to 10th	Night	16% 7% 34% 31% 11% 1	760
	11th to 20th	Night	16% 8% 27% 29% 17% 2	760
	21st to end	Night	20% 10% 29% 28% 11% 2	760
October	1st to 10th	Night	24% 13% 28% 24% 10% 2	760
	11th to 20th	Night	19% 15% 33% 21% 10% 1	760
	21st to end	Night	28% 16% 33% 18% 6%	836
November	1st to 10th	Night	19% 18% 36% 20% 7% 1	755
	11th to 20th	Night	24% 24% 29% 16% 5% 1	760
	21st to end	Night	22% 22% 37% 15% 4 1	760
December	1st to 10th	Night	26% 21% 34% 15% 4	760
	11th to 20th	Night	25% 23% 35% 16% 2	760
	21st to end	Night	26% 24% 35% 14% 2	836

Page generated at 2024-11-01 22:47:35. Version ac07

Copyright © 2024 Attilla Danko.