Rutherford County Astronomical Society - Site 1
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rutherford County Astronomical Society - Site 1 clear sky chart from 2005-11-06 to 2024-11-25.

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	14% 5% 2 5% 4 4 4 4 6% 8% 43%	101360
	Night	15% 6% 2 6% 4 4 4 4 5% 7% 43%	98072
Transparency	Day	21% 47% 7% 12% 10% 4	105089
	Night	22% 48% 6% 11% 11% 4	102482
Seeing	Day	17% 8% 21% 25% 19% 11%	15217
	Night	17% 5% 22% 32% 21% 3	25284

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	17% 4 1 3 3 2 3 2 5% 6% 53%	2836
	11th to 20th	Day	15% 7% 2 4 3 3 3 3 3 4 54%	2840
	21st to end	Day	25% 4 2 3 2 2 3 3 4 5% 46%	3124
February	1st to 10th	Day	16% 6% 2 4 4 4 3 4 6% 8% 43%	1752
	11th to 20th	Day	20% 7% 2 4 3 3 2 3 5% 5% 45%	1848
	21st to end	Day	19% 6% 3 5% 5% 3 4 3 5% 6% 40%	1570
March	1st to 10th	Day	24% 6% 2 5% 3 3 3 3 4 5% 42%	3425
	11th to 20th	Day	12% 4 2 4 3 4 4 3 4 6% 53%	3480
	21st to end	Day	21% 5% 1 4 3 3 3 4 5% 6% 44%	3815
April	1st to 10th	Day	12% 4 1 5% 4 4 4 3 6% 8% 49%	2090
	11th to 20th	Day	14% 5% 2 4 4 4 4 4 6% 7% 47%	2239
	21st to end	Day	14% 4 1 5% 4 4 4 3 5% 7% 47%	2470
May	1st to 10th	Day	11% 7% 3 7% 4 5% 6% 5% 7% 8% 38%	4082
	11th to 20th	Day	17% 8% 3 7% 5% 4 4 4 6% 7% 37%	4081
	21st to end	Day	8% 5% 2 6% 4 4 5% 5% 7% 10% 44%	4476
June	1st to 10th	Day	11% 5% 2 7% 5% 5% 5% 6% 8% 11% 34%	2470
	11th to 20th	Day	7% 5% 2 6% 6% 5% 6% 5% 8% 11% 39%	2470
	21st to end	Day	7% 4 2 6% 5% 7% 6% 6% 8% 10% 39%	2470
July	1st to 10th	Day	8% 5% 2 7% 5% 6% 6% 6% 7% 11% 36%	4120
	11th to 20th	Day	8% 5% 2 7% 5% 5% 6% 5% 8% 11% 36%	4120
	21st to end	Day	12% 7% 3 10% 7% 7% 8% 6% 9% 11% 21%	4466
August	1st to 10th	Day	17% 6% 3 7% 5% 5% 6% 5% 7% 10% 29%	4104
	11th to 20th	Day	9% 5% 2 6% 5% 5% 6% 6% 8% 11% 37%	4044
	21st to end	Day	7% 4 2 4 4 4 4 3 6% 9% 53%	4224
September	1st to 10th	Day	9% 4 2 7% 5% 5% 5% 5% 6% 9% 42%	2090
	11th to 20th	Day	15% 6% 2 6% 5% 4 4 3 5% 8% 40%	2090
	21st to end	Day	17% 6% 2 6% 4 3 4 4 5% 6% 42%	2090
October	1st to 10th	Day	16% 4 2 4 2 2 3 2 4 6% 56%	2024
	11th to 20th	Day	13% 4 1 4 2 2 2 2 4 4 61%	1900
	21st to end	Day	14% 5% 2 4 2 3 3 3 3 4 58%	2090
November	1st to 10th	Day	15% 4 1 5% 3 3 3 2 4 6% 54%	1927
	11th to 20th	Day	14% 6% 2 4 3 3 3 3 4 6% 53%	1800
	21st to end	Day	16% 5% 2 3 3 2 3 4 5% 6% 52%	1746
December	1st to 10th	Day	19% 7% 2 5% 3 4 4 4 4 7% 41%	1710
	11th to 20th	Day	17% 4 2 4 2 3 2 3 5% 5% 52%	2153
	21st to end	Day	21% 5% 2 4 2 3 4 3 5% 6% 45%	3124
January	1st to 10th	Night	17% 4 1 4 4 3 3 3 4 5% 51%	4109
	11th to 20th	Night	13% 6% 2 6% 4 3 3 4 5% 5% 50%	4120
	21st to end	Night	25% 6% 1 4 3 3 3 3 4 5% 43%	4532
February	1st to 10th	Night	16% 5% 2 5% 3 3 4 3 5% 5% 48%	2423
	11th to 20th	Night	20% 6% 2 4 4 3 4 3 5% 4 45%	2218
	21st to end	Night	17% 7% 3 6% 4 4 5% 3 5% 6% 42%	1884
March	1st to 10th	Night	23% 7% 2 5% 4 4 4 3 4 6% 37%	3427
	11th to 20th	Night	11% 5% 2 4 3 3 4 4 5% 8% 52%	3480
	21st to end	Night	20% 5% 2 5% 4 3 4 3 5% 6% 43%	3817
April	1st to 10th	Night	13% 5% 2 5% 4 3 4 3 6% 6% 49%	2090
	11th to 20th	Night	13% 5% 2 5% 4 3 3 3 6% 7% 49%	1904
	21st to end	Night	12% 5% 2 5% 4 4 4 4 4 6% 50%	1710
May	1st to 10th	Night	15% 6% 2 7% 5% 4 4 4 6% 8% 39%	2813
	11th to 20th	Night	17% 7% 2 7% 5% 4 4 3 5% 7% 37%	2812
	21st to end	Night	9% 5% 2 6% 4 5% 5% 4 7% 10% 42%	3079
June	1st to 10th	Night	11% 6% 2 7% 6% 5% 5% 6% 8% 13% 32%	1710
	11th to 20th	Night	10% 7% 2 5% 5% 4 6% 5% 6% 11% 38%	1710
	21st to end	Night	8% 6% 2 6% 6% 5% 6% 5% 7% 11% 37%	1710
July	1st to 10th	Night	10% 7% 3 7% 6% 6% 7% 6% 8% 9% 30%	2840
	11th to 20th	Night	10% 5% 2 7% 6% 6% 6% 6% 9% 11% 34%	2840
	21st to end	Night	14% 8% 4 10% 7% 6% 7% 6% 9% 10% 20%	3087
August	1st to 10th	Night	17% 8% 3 8% 6% 5% 4 5% 7% 9% 27%	2825
	11th to 20th	Night	15% 6% 3 8% 4 6% 6% 5% 8% 8% 31%	2785
	21st to end	Night	7% 5% 3 6% 4 5% 5% 4 7% 8% 45%	3394
September	1st to 10th	Night	11% 6% 2 6% 6% 5% 5% 4 7% 8% 40%	2090
	11th to 20th	Night	17% 6% 3 8% 6% 4 5% 4 5% 8% 34%	2090
	21st to end	Night	18% 6% 2 6% 4 3 4 3 5% 6% 42%	2090
October	1st to 10th	Night	17% 5% 1 4 3 4 3 3 4 5% 50%	2156
	11th to 20th	Night	15% 6% 2 4 3 2 3 2 4 6% 53%	2280
	21st to end	Night	14% 3 2 4 2 3 3 2 4 4 58%	2508
November	1st to 10th	Night	16% 4 2 5% 3 3 3 2 3 5% 53%	2366
	11th to 20th	Night	14% 5% 2 5% 3 3 4 3 4 6% 52%	2600
	21st to end	Night	15% 4 2 4 3 3 4 3 5% 7% 50%	2529
December	1st to 10th	Night	21% 7% 2 5% 3 3 3 2 5% 5% 43%	2470
	11th to 20th	Night	17% 5% 2 4 3 3 3 2 4 6% 52%	3042
	21st to end	Night	22% 6% 2 5% 3 4 4 3 4 7% 41%	4532

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	21% 36% 2 17% 17% 7%	2837
	11th to 20th	Day	22% 36% 3 9% 25% 4	2840
	21st to end	Day	27% 39% 2 11% 18% 3	3124
February	1st to 10th	Day	14% 65% 3 9% 7% 2	1752
	11th to 20th	Day	17% 64% 2 7% 8% 2	1858
	21st to end	Day	17% 66% 2 4 8% 2	1570
March	1st to 10th	Day	33% 41% 4 9% 6% 6%	3425
	11th to 20th	Day	16% 41% 4 9% 20% 10%	3480
	21st to end	Day	24% 40% 3 14% 16% 3	3815
April	1st to 10th	Day	14% 65% 4 6% 9% 2	2090
	11th to 20th	Day	15% 66% 4 7% 5% 2	2239
	21st to end	Day	13% 65% 4 10% 7% 1	2470
May	1st to 10th	Day	27% 43% 9% 13% 7% 1	4120
	11th to 20th	Day	30% 40% 5% 16% 8%	4085
	21st to end	Day	18% 42% 12% 14% 12% 2	4489
June	1st to 10th	Day	15% 66% 8% 7% 4 1	2470
	11th to 20th	Day	11% 67% 8% 9% 5%	2470
	21st to end	Day	14% 66% 7% 9% 4	2470
July	1st to 10th	Day	24% 42% 14% 14% 5%	4055
	11th to 20th	Day	24% 41% 19% 14% 1	4051
	21st to end	Day	40% 40% 9% 8% 3 1	4324
August	1st to 10th	Day	34% 39% 11% 14% 2	4091
	11th to 20th	Day	19% 41% 17% 12% 8% 2	4083
	21st to end	Day	12% 38% 9% 25% 14% 1	4224
September	1st to 10th	Day	14% 62% 5% 9% 8% 1	2090
	11th to 20th	Day	18% 61% 6% 7% 7% 2	2090
	21st to end	Day	19% 61% 5% 8% 6% 1	2090
October	1st to 10th	Day	17% 37% 5% 13% 21% 7%	3362
	11th to 20th	Day	9% 36% 2 10% 20% 23%	3140
	21st to end	Day	18% 36% 2 17% 13% 15%	3428
November	1st to 10th	Day	20% 55% 3 9% 10% 3	1927
	11th to 20th	Day	16% 57% 2 9% 12% 3	1800
	21st to end	Day	14% 59% 3 10% 11% 3	1746
December	1st to 10th	Day	21% 60% 3 10% 4 3	1710
	11th to 20th	Day	16% 47% 2 10% 16% 9%	2150
	21st to end	Day	26% 38% 4 16% 14% 2	3124
January	1st to 10th	Night	22% 39% 3 10% 20% 6%	4109
	11th to 20th	Night	22% 38% 3 10% 21% 5%	4120
	21st to end	Night	29% 40% 2 10% 15% 4	4532
February	1st to 10th	Night	14% 65% 3 8% 9% 1	2423
	11th to 20th	Night	18% 64% 3 6% 7% 2	2219
	21st to end	Night	16% 65% 3 6% 7% 3	1884
March	1st to 10th	Night	35% 43% 6% 7% 6% 3	3427
	11th to 20th	Night	14% 41% 3 11% 17% 14%	3480
	21st to end	Night	26% 40% 3 11% 13% 6%	3817
April	1st to 10th	Night	14% 65% 4 6% 9% 2	2090
	11th to 20th	Night	14% 66% 4 8% 5% 3	1904
	21st to end	Night	13% 65% 4 10% 7% 1	1710
May	1st to 10th	Night	28% 42% 8% 14% 7% 1	2840
	11th to 20th	Night	25% 43% 8% 14% 10%	2813
	21st to end	Night	18% 43% 8% 20% 10% 1	3087
June	1st to 10th	Night	15% 67% 5% 8% 3 1	1710
	11th to 20th	Night	12% 68% 8% 8% 5%	1710
	21st to end	Night	13% 66% 9% 6% 6%	1710
July	1st to 10th	Night	30% 41% 12% 12% 4	2795
	11th to 20th	Night	26% 42% 17% 15% 1	2786
	21st to end	Night	41% 41% 8% 8% 2 1	2988
August	1st to 10th	Night	37% 41% 12% 9% 1	2814
	11th to 20th	Night	31% 42% 13% 9% 6%	2812
	21st to end	Night	17% 40% 8% 22% 12% 2	3394
September	1st to 10th	Night	14% 61% 7% 9% 7% 1	2090
	11th to 20th	Night	20% 62% 6% 6% 5% 1	2090
	21st to end	Night	20% 61% 6% 9% 4	2090
October	1st to 10th	Night	23% 38% 6% 11% 16% 7%	3598
	11th to 20th	Night	10% 36% 3 12% 20% 19%	3779
	21st to end	Night	18% 36% 2 14% 18% 12%	4120
November	1st to 10th	Night	21% 55% 3 9% 8% 4	2366
	11th to 20th	Night	16% 57% 3 7% 12% 6%	2600
	21st to end	Night	14% 58% 3 10% 12% 2	2529
December	1st to 10th	Night	22% 60% 3 8% 6% 2	2470
	11th to 20th	Night	15% 49% 3 9% 18% 7%	3044
	21st to end	Night	29% 37% 4 15% 14% 1	4532

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% 16% 30% 23% 6%	270
	11th to 20th	Day	28% 18% 27% 20% 7% 1	270
	21st to end	Day	23% 15% 39% 19% 5%	297
February	1st to 10th	Day	21% 16% 34% 21% 6% 1	270
	11th to 20th	Day	35% 20% 31% 11% 3	270
	21st to end	Day	28% 22% 32% 14% 4	225
March	1st to 10th	Day	22% 12% 30% 25% 10% 2	450
	11th to 20th	Day	20% 12% 34% 27% 6% 1	460
	21st to end	Day	23% 15% 28% 25% 9% 1	506
April	1st to 10th	Day	18% 16% 26% 25% 11% 3	460
	11th to 20th	Day	16% 14% 27% 24% 16% 4	452
	21st to end	Day	18% 10% 25% 27% 14% 7%	460
May	1st to 10th	Day	14% 11% 28% 27% 14% 7%	463
	11th to 20th	Day	17% 6% 16% 30% 22% 10%	487
	21st to end	Day	16% 4 15% 24% 24% 16%	529
June	1st to 10th	Day	12% 3 17% 30% 23% 15%	490
	11th to 20th	Day	10% 2 16% 26% 25% 21%	490
	21st to end	Day	11% 2 14% 30% 25% 18%	490
July	1st to 10th	Day	9% 2 9% 23% 30% 27%	485
	11th to 20th	Day	7% 1 8% 25% 31% 27%	484
	21st to end	Day	8% 1 9% 27% 31% 24%	532
August	1st to 10th	Day	16% 2 13% 23% 26% 19%	486
	11th to 20th	Day	12% 2 11% 25% 32% 17%	479
	21st to end	Day	12% 2 10% 22% 28% 27%	539
September	1st to 10th	Day	10% 2 13% 23% 31% 21%	490
	11th to 20th	Day	20% 3 11% 18% 30% 19%	490
	21st to end	Day	23% 3 18% 23% 26% 8%	490
October	1st to 10th	Day	18% 5% 15% 24% 25% 13%	490
	11th to 20th	Day	14% 7% 18% 31% 23% 7%	490
	21st to end	Day	20% 6% 18% 30% 20% 6%	539
November	1st to 10th	Day	23% 7% 23% 28% 16% 5%	465
	11th to 20th	Day	19% 10% 32% 26% 10% 2	300
	21st to end	Day	12% 11% 30% 29% 15% 4	282
December	1st to 10th	Day	27% 10% 30% 26% 7%	270
	11th to 20th	Day	22% 11% 32% 23% 10% 1	270
	21st to end	Day	25% 14% 31% 21% 9% 1	297
January	1st to 10th	Night	19% 10% 30% 33% 8%	760
	11th to 20th	Night	19% 8% 35% 33% 5%	760
	21st to end	Night	19% 8% 37% 33% 3	836
February	1st to 10th	Night	17% 9% 33% 38% 4	760
	11th to 20th	Night	21% 11% 37% 29% 2	743
	21st to end	Night	18% 11% 37% 31% 3	628
March	1st to 10th	Night	18% 8% 29% 38% 6%	760
	11th to 20th	Night	19% 9% 33% 31% 8% 1	760
	21st to end	Night	19% 8% 32% 34% 7%	836
April	1st to 10th	Night	16% 12% 29% 32% 11%	760
	11th to 20th	Night	15% 12% 23% 33% 15% 1	723
	21st to end	Night	15% 5% 23% 38% 19% 1	570
May	1st to 10th	Night	14% 3 26% 34% 22% 1	570
	11th to 20th	Night	18% 4 19% 31% 26% 2	561
	21st to end	Night	16% 2 9% 31% 37% 5%	617
June	1st to 10th	Night	12% 2 10% 34% 36% 5%	570
	11th to 20th	Night	12% 3 9% 29% 34% 13%	570
	21st to end	Night	9% 2 9% 28% 46% 7%	570
July	1st to 10th	Night	12% 2 7% 21% 47% 11%	555
	11th to 20th	Night	10% 8% 20% 48% 14%	552
	21st to end	Night	8% 2 6% 26% 47% 12%	624
August	1st to 10th	Night	14% 3 8% 25% 41% 9%	567
	11th to 20th	Night	13% 3 6% 27% 41% 10%	564
	21st to end	Night	12% 2 7% 23% 47% 9%	717
September	1st to 10th	Night	12% 2 8% 26% 42% 9%	760
	11th to 20th	Night	18% 2 11% 24% 37% 8%	760
	21st to end	Night	20% 3 15% 31% 29% 3	760
October	1st to 10th	Night	18% 3 17% 28% 28% 7%	760
	11th to 20th	Night	18% 5% 22% 32% 21% 2	760
	21st to end	Night	15% 5% 21% 36% 21% 2	836
November	1st to 10th	Night	18% 4 19% 38% 19% 3	780
	11th to 20th	Night	16% 6% 25% 40% 12% 1	800
	21st to end	Night	17% 6% 24% 38% 15% 1	779
December	1st to 10th	Night	23% 6% 27% 36% 8%	760
	11th to 20th	Night	20% 4 26% 39% 10% 1	760
	21st to end	Night	27% 6% 27% 32% 8%	836

Page generated at 2024-11-22 08:02:28. Version ac07

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