Antique Airfield-IA27
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Antique Airfield-IA27 clear sky chart from 2005-11-06 to 2024-11-30.

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	13% 8% 3 7% 5% 4 4 4 6% 7% 40%	101631
	Night	12% 8% 3 7% 4 4 4 3 5% 6% 43%	98058
Transparency	Day	43% 4 12% 25% 15% 2	105270
	Night	42% 3 12% 24% 17% 3	102559
Seeing	Day	16% 10% 29% 26% 15% 4	15878
	Night	16% 10% 32% 30% 12% 1	25743

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	10% 12% 4 16% 7% 5% 5% 4 5% 7% 25%	2527
	11th to 20th	Day	10% 12% 5% 10% 8% 7% 8% 3 6% 5% 26%	2791
	21st to end	Day	15% 18% 7% 15% 6% 4 4 3 4 5% 20%	3135
February	1st to 10th	Day	13% 11% 4 10% 7% 4 5% 4 5% 6% 29%	1710
	11th to 20th	Day	13% 10% 4 8% 5% 5% 5% 3 5% 7% 35%	1664
	21st to end	Day	16% 9% 4 8% 5% 4 4 3 6% 6% 36%	1565
March	1st to 10th	Day	16% 11% 3 7% 4 3 3 3 4 6% 39%	3375
	11th to 20th	Day	11% 7% 3 6% 4 3 5% 3 6% 6% 46%	3480
	21st to end	Day	23% 13% 4 8% 5% 4 4 4 5% 6% 25%	3867
April	1st to 10th	Day	17% 10% 3 6% 4 4 4 4 5% 6% 37%	2280
	11th to 20th	Day	16% 10% 3 7% 6% 4 4 3 5% 6% 37%	2254
	21st to end	Day	22% 7% 3 8% 5% 5% 4 3 5% 6% 34%	2318
May	1st to 10th	Day	16% 8% 3 7% 5% 5% 5% 4 6% 7% 35%	4082
	11th to 20th	Day	16% 7% 3 7% 4 4 4 4 5% 7% 39%	4390
	21st to end	Day	13% 6% 2 5% 4 4 4 3 5% 7% 46%	4824
June	1st to 10th	Day	9% 4 2 6% 4 4 4 4 7% 9% 46%	2660
	11th to 20th	Day	9% 5% 1 5% 5% 4 5% 4 7% 9% 46%	2660
	21st to end	Day	10% 5% 2 6% 5% 5% 5% 5% 7% 9% 41%	2660
July	1st to 10th	Day	9% 7% 3 7% 5% 6% 5% 4 7% 9% 36%	4440
	11th to 20th	Day	6% 4 2 5% 4 4 5% 4 6% 10% 51%	4440
	21st to end	Day	5% 4 2 5% 5% 6% 5% 5% 8% 12% 43%	4479
August	1st to 10th	Day	7% 4 2 6% 4 4 5% 4 7% 11% 46%	4104
	11th to 20th	Day	12% 7% 2 7% 4 4 5% 4 6% 8% 41%	4013
	21st to end	Day	8% 5% 2 5% 4 4 4 4 6% 9% 50%	4180
September	1st to 10th	Day	14% 4 2 4 3 3 4 2 5% 7% 52%	2280
	11th to 20th	Day	10% 4 2 5% 3 3 4 4 7% 9% 50%	2280
	21st to end	Day	10% 6% 2 5% 4 4 5% 3 4 7% 50%	1985
October	1st to 10th	Day	14% 6% 3 5% 3 3 3 3 4 6% 49%	1900
	11th to 20th	Day	15% 7% 3 6% 3 3 3 3 3 5% 49%	1900
	21st to end	Day	15% 10% 3 7% 4 3 3 2 4 5% 43%	2090
November	1st to 10th	Day	10% 8% 2 4 3 5% 4 4 5% 8% 46%	1814
	11th to 20th	Day	14% 9% 3 7% 4 4 4 3 4 7% 41%	1666
	21st to end	Day	16% 10% 3 7% 4 4 4 2 5% 7% 39%	1597
December	1st to 10th	Day	13% 12% 4 11% 5% 4 4 3 4 6% 35%	1520
	11th to 20th	Day	12% 10% 3 9% 5% 4 5% 3 6% 9% 34%	1918
	21st to end	Day	21% 16% 8% 13% 5% 5% 4 2 4 4 18%	2783
January	1st to 10th	Night	11% 11% 6% 16% 6% 5% 4 3 4 5% 29%	4428
	11th to 20th	Night	11% 15% 6% 12% 5% 4 6% 4 7% 5% 25%	4175
	21st to end	Night	16% 16% 6% 13% 5% 4 4 3 4 6% 23%	4532
February	1st to 10th	Night	14% 11% 4 9% 5% 5% 4 4 5% 6% 34%	2470
	11th to 20th	Night	12% 10% 3 7% 5% 5% 4 3 5% 6% 40%	2403
	21st to end	Night	14% 10% 3 8% 5% 4 4 2 4 4 42%	1889
March	1st to 10th	Night	17% 10% 2 6% 4 3 3 3 3 4 44%	3494
	11th to 20th	Night	12% 7% 2 6% 3 3 3 2 4 6% 52%	3480
	21st to end	Night	21% 12% 6% 10% 5% 4 4 3 4 5% 27%	3764
April	1st to 10th	Night	13% 9% 2 6% 4 3 4 4 5% 7% 43%	1900
	11th to 20th	Night	14% 8% 3 6% 5% 5% 5% 3 4 6% 42%	1875
	21st to end	Night	17% 7% 3 6% 3 3 4 4 5% 6% 41%	1857
May	1st to 10th	Night	17% 8% 3 6% 5% 4 4 3 5% 6% 37%	2823
	11th to 20th	Night	14% 6% 2 6% 4 4 4 3 5% 7% 45%	2512
	21st to end	Night	10% 5% 2 6% 4 4 4 4 5% 7% 50%	2743
June	1st to 10th	Night	7% 5% 2 4 4 3 5% 4 8% 9% 50%	1520
	11th to 20th	Night	7% 5% 2 4 3 3 5% 3 6% 10% 49%	1520
	21st to end	Night	8% 5% 1 5% 5% 3 5% 5% 6% 9% 48%	1520
July	1st to 10th	Night	11% 5% 2 6% 4 4 5% 4 6% 8% 45%	2530
	11th to 20th	Night	4 2 1 4 4 3 4 4 5% 8% 61%	2530
	21st to end	Night	6% 4 2 5% 4 4 4 4 7% 9% 51%	3081
August	1st to 10th	Night	3 3 1 4 4 4 4 4 6% 9% 58%	2836
	11th to 20th	Night	10% 5% 2 5% 3 3 3 3 5% 6% 55%	2824
	21st to end	Night	6% 3 1 4 4 4 4 4 5% 9% 56%	3476
September	1st to 10th	Night	10% 4 2 4 2 3 3 3 5% 6% 56%	1900
	11th to 20th	Night	10% 4 2 5% 4 4 4 3 4 6% 54%	1900
	21st to end	Night	9% 4 1 4 3 3 3 3 4 7% 58%	2172
October	1st to 10th	Night	12% 6% 2 5% 3 3 3 3 4 4 53%	2280
	11th to 20th	Night	14% 6% 3 4 3 3 3 3 4 6% 52%	2280
	21st to end	Night	16% 7% 2 8% 4 4 3 3 4 6% 44%	2508
November	1st to 10th	Night	10% 6% 2 4 3 3 3 3 5% 7% 55%	2484
	11th to 20th	Night	13% 9% 2 6% 4 4 3 4 5% 6% 44%	2730
	21st to end	Night	16% 10% 3 7% 4 3 4 3 4 5% 41%	2799
December	1st to 10th	Night	13% 11% 3 8% 5% 4 4 3 4 6% 40%	2660
	11th to 20th	Night	13% 9% 3 10% 6% 3 3 3 4 5% 40%	3279
	21st to end	Night	19% 17% 8% 11% 5% 4 4 2 3 4 22%	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	59% 3 13% 16% 8% 1	2528
	11th to 20th	Day	61% 2 11% 20% 7%	2791
	21st to end	Day	68% 3 9% 13% 6% 1	3135
February	1st to 10th	Day	54% 4 13% 18% 10% 1	1710
	11th to 20th	Day	49% 4 12% 24% 11% 1	1673
	21st to end	Day	49% 3 11% 24% 12% 2	1565
March	1st to 10th	Day	48% 3 10% 23% 16% 1	3375
	11th to 20th	Day	38% 3 13% 25% 19% 1	3480
	21st to end	Day	60% 3 16% 16% 4 1	3867
April	1st to 10th	Day	48% 5% 11% 27% 9%	2280
	11th to 20th	Day	48% 4 10% 24% 13% 2	2254
	21st to end	Day	53% 3 11% 20% 12% 1	2318
May	1st to 10th	Day	48% 4 12% 21% 14% 1	4120
	11th to 20th	Day	47% 3 11% 28% 11%	4394
	21st to end	Day	38% 5% 10% 27% 19% 1	4837
June	1st to 10th	Day	34% 6% 17% 28% 14% 2	2660
	11th to 20th	Day	33% 6% 13% 24% 21% 3	2660
	21st to end	Day	38% 6% 16% 24% 14% 2	2660
July	1st to 10th	Day	44% 4 13% 26% 11% 2	4371
	11th to 20th	Day	30% 4 14% 33% 18% 1	4365
	21st to end	Day	32% 5% 20% 27% 16% 1	4338
August	1st to 10th	Day	32% 5% 15% 32% 14% 1	4090
	11th to 20th	Day	42% 3 13% 26% 17%	4052
	21st to end	Day	32% 3 16% 30% 15% 3	4179
September	1st to 10th	Day	33% 4 10% 26% 22% 5%	2280
	11th to 20th	Day	30% 5% 10% 32% 20% 2	2280
	21st to end	Day	34% 4 11% 30% 20% 2	1985
October	1st to 10th	Day	24% 2 5% 18% 48% 3	3160
	11th to 20th	Day	26% 1 8% 26% 30% 8%	3140
	21st to end	Day	40% 2 9% 28% 18% 2	3428
November	1st to 10th	Day	36% 4 15% 24% 18% 3	1814
	11th to 20th	Day	43% 3 11% 24% 17% 1	1666
	21st to end	Day	47% 3 14% 24% 13%	1597
December	1st to 10th	Day	51% 3 14% 22% 8% 1	1520
	11th to 20th	Day	48% 3 15% 24% 10%	1915
	21st to end	Day	70% 3 8% 13% 5% 1	2783
January	1st to 10th	Night	59% 2 10% 19% 9% 1	4428
	11th to 20th	Night	59% 2 11% 15% 11% 1	4175
	21st to end	Night	64% 2 11% 16% 6% 1	4532
February	1st to 10th	Night	52% 4 10% 22% 11% 1	2470
	11th to 20th	Night	45% 3 11% 26% 13% 2	2404
	21st to end	Night	47% 3 8% 23% 15% 4	1889
March	1st to 10th	Night	45% 2 9% 25% 18% 1	3494
	11th to 20th	Night	36% 2 11% 31% 16% 5%	3480
	21st to end	Night	61% 3 18% 13% 5%	3764
April	1st to 10th	Night	41% 4 11% 27% 15% 2	1900
	11th to 20th	Night	44% 3 9% 25% 16% 3	1875
	21st to end	Night	43% 4 13% 23% 15% 2	1857
May	1st to 10th	Night	48% 4 11% 20% 16% 1	2850
	11th to 20th	Night	39% 4 14% 26% 15% 1	2513
	21st to end	Night	35% 5% 11% 23% 24% 2	2751
June	1st to 10th	Night	30% 5% 18% 27% 17% 3	1520
	11th to 20th	Night	29% 5% 13% 28% 21% 4	1520
	21st to end	Night	32% 5% 16% 25% 19% 4	1520
July	1st to 10th	Night	37% 3 13% 29% 13% 4	2490
	11th to 20th	Night	22% 3 16% 35% 22% 2	2482
	21st to end	Night	29% 5% 20% 25% 19% 2	2983
August	1st to 10th	Night	23% 4 17% 36% 18% 2	2826
	11th to 20th	Night	31% 3 14% 32% 19% 1	2851
	21st to end	Night	27% 4 14% 32% 17% 5%	3476
September	1st to 10th	Night	29% 4 8% 27% 26% 5%	1900
	11th to 20th	Night	33% 4 8% 31% 20% 4	1900
	21st to end	Night	28% 3 9% 31% 25% 3	2172
October	1st to 10th	Night	23% 2 5% 21% 44% 4	3800
	11th to 20th	Night	27% 2 8% 24% 29% 10%	3779
	21st to end	Night	43% 2 8% 23% 20% 3	4120
November	1st to 10th	Night	30% 4 16% 26% 20% 4	2484
	11th to 20th	Night	40% 3 12% 28% 15% 2	2730
	21st to end	Night	47% 2 11% 26% 14% 1	2799
December	1st to 10th	Night	47% 3 13% 25% 11% 1	2660
	11th to 20th	Night	48% 3 11% 27% 10% 1	3281
	21st to end	Night	68% 3 7% 15% 6% 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	21% 14% 33% 21% 9% 1	270
	11th to 20th	Day	24% 14% 41% 19% 2	270
	21st to end	Day	23% 17% 38% 20% 3	297
February	1st to 10th	Day	21% 19% 37% 19% 3	270
	11th to 20th	Day	22% 15% 36% 21% 6%	270
	21st to end	Day	23% 14% 44% 14% 4 1	225
March	1st to 10th	Day	21% 14% 47% 14% 4	270
	11th to 20th	Day	23% 14% 35% 22% 6%	270
	21st to end	Day	36% 17% 30% 14% 3 1	325
April	1st to 10th	Day	23% 14% 37% 20% 6% 1	460
	11th to 20th	Day	22% 15% 33% 20% 9% 1	452
	21st to end	Day	24% 15% 34% 19% 7% 1	498
May	1st to 10th	Day	21% 14% 33% 21% 10%	653
	11th to 20th	Day	21% 12% 26% 25% 13% 3	675
	21st to end	Day	16% 8% 30% 27% 16% 4	734
June	1st to 10th	Day	8% 5% 24% 33% 23% 7%	680
	11th to 20th	Day	11% 4 27% 35% 19% 4	680
	21st to end	Day	11% 9% 33% 29% 16% 3	680
July	1st to 10th	Day	9% 4 16% 32% 26% 13%	671
	11th to 20th	Day	8% 4 22% 34% 24% 7%	668
	21st to end	Day	7% 3 20% 36% 28% 5%	739
August	1st to 10th	Day	9% 3 21% 36% 26% 6%	676
	11th to 20th	Day	12% 4 19% 31% 27% 7%	650
	21st to end	Day	9% 2 19% 34% 27% 10%	539
September	1st to 10th	Day	15% 4 17% 31% 27% 5%	490
	11th to 20th	Day	9% 3 22% 35% 23% 9%	490
	21st to end	Day	12% 9% 29% 25% 20% 4	310
October	1st to 10th	Day	21% 5% 29% 24% 14% 7%	300
	11th to 20th	Day	14% 23% 34% 20% 8% 1	300
	21st to end	Day	23% 18% 34% 18% 6% 1	330
November	1st to 10th	Day	16% 10% 39% 25% 7% 2	300
	11th to 20th	Day	21% 18% 33% 19% 7% 2	300
	21st to end	Day	25% 12% 39% 19% 4	299
December	1st to 10th	Day	15% 14% 41% 20% 7% 3	270
	11th to 20th	Day	19% 16% 36% 21% 7% 1	270
	21st to end	Day	28% 22% 31% 17% 2	297
January	1st to 10th	Night	16% 14% 42% 20% 8%	950
	11th to 20th	Night	17% 15% 39% 22% 7% 1	950
	21st to end	Night	18% 14% 38% 24% 5%	1045
February	1st to 10th	Night	21% 12% 39% 24% 5%	950
	11th to 20th	Night	17% 13% 38% 28% 3	929
	21st to end	Night	20% 14% 39% 22% 4 1	633
March	1st to 10th	Night	17% 14% 39% 21% 8%	623
	11th to 20th	Night	18% 12% 36% 26% 7%	570
	21st to end	Night	27% 9% 35% 22% 5% 1	627
April	1st to 10th	Night	17% 13% 42% 24% 4	570
	11th to 20th	Night	19% 13% 34% 27% 6% 1	563
	21st to end	Night	20% 11% 33% 27% 8% 1	570
May	1st to 10th	Night	16% 9% 35% 33% 7% 1	570
	11th to 20th	Night	19% 7% 30% 31% 12% 1	561
	21st to end	Night	13% 6% 28% 35% 17% 1	617
June	1st to 10th	Night	9% 4 23% 41% 20% 2	570
	11th to 20th	Night	9% 4 25% 43% 18% 1	570
	21st to end	Night	10% 4 29% 41% 16% 1	570
July	1st to 10th	Night	8% 2 13% 39% 36% 2	555
	11th to 20th	Night	5% 2 18% 45% 27% 3	552
	21st to end	Night	8% 2 15% 44% 29% 2	624
August	1st to 10th	Night	5% 3 16% 48% 26% 2	567
	11th to 20th	Night	9% 2 15% 43% 28% 4	564
	21st to end	Night	8% 2 13% 44% 30% 3	627
September	1st to 10th	Night	12% 3 19% 36% 25% 3	570
	11th to 20th	Night	12% 2 20% 37% 25% 3	570
	21st to end	Night	11% 5% 28% 34% 20% 3	665
October	1st to 10th	Night	15% 6% 29% 32% 17% 2	760
	11th to 20th	Night	16% 13% 33% 30% 8%	760
	21st to end	Night	19% 12% 35% 27% 8%	836
November	1st to 10th	Night	15% 10% 36% 31% 8%	780
	11th to 20th	Night	18% 14% 40% 22% 5%	930
	21st to end	Night	22% 12% 35% 24% 7%	1000
December	1st to 10th	Night	18% 14% 38% 23% 6% 1	950
	11th to 20th	Night	20% 12% 35% 27% 6%	950
	21st to end	Night	24% 15% 35% 23% 3	1045

Page generated at 2024-11-27 16:30:49. Version ac07

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