Liberty University
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Liberty University clear sky chart from 2005-11-06 to 2024-03-23.

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% 5% 3 5% 5% 6% 8% 43%	78735
	Night	14% 6% 2 5% 5% 3 4 4 5% 7% 45%	81112
Transparency	Day	39% 6% 11% 23% 17% 4	78456
	Night	38% 6% 10% 22% 19% 5%	80910
Seeing	Day	19% 11% 24% 25% 15% 6%	14203
	Night	17% 9% 26% 31% 16% 2	24358

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 2 4 3 2 3 5% 4 6% 50%	2836
	11th to 20th	Day	15% 6% 2 6% 5% 3 3 4 5% 6% 45%	2840
	21st to end	Day	21% 7% 3 6% 4 2 4 4 4 5% 41%	3124
February	1st to 10th	Day	13% 7% 2 5% 5% 3 5% 5% 7% 7% 42%	1710
	11th to 20th	Day	20% 5% 2 4 4 3 4 4 5% 7% 43%	1663
	21st to end	Day	20% 7% 3 6% 5% 3 4 3 5% 7% 38%	1669
March	1st to 10th	Day	14% 6% 2 4 4 2 4 4 4 6% 50%	2090
	11th to 20th	Day	16% 6% 3 5% 4 3 5% 4 6% 7% 41%	2090
	21st to end	Day	17% 6% 4 5% 6% 3 4 4 5% 6% 40%	2200
April	1st to 10th	Day	11% 4 2 4 5% 2 4 4 5% 7% 51%	2088
	11th to 20th	Day	13% 6% 2 5% 4 3 4 4 5% 8% 47%	2134
	21st to end	Day	16% 6% 2 5% 5% 3 4 3 5% 7% 42%	2214
May	1st to 10th	Day	13% 6% 3 6% 4 4 5% 6% 6% 9% 39%	2340
	11th to 20th	Day	17% 5% 2 5% 5% 4 5% 6% 6% 9% 37%	2301
	21st to end	Day	13% 5% 2 5% 5% 4 5% 5% 7% 9% 39%	2531
June	1st to 10th	Day	10% 4 2 5% 6% 3 5% 5% 6% 10% 45%	2454
	11th to 20th	Day	11% 4 2 5% 5% 3 5% 6% 7% 11% 40%	2520
	21st to end	Day	8% 4 2 5% 5% 4 5% 5% 8% 11% 41%	2370
July	1st to 10th	Day	9% 5% 2 6% 6% 4 6% 6% 7% 10% 39%	2340
	11th to 20th	Day	6% 3 2 5% 6% 4 7% 7% 8% 11% 40%	2340
	21st to end	Day	9% 5% 3 6% 6% 4 7% 7% 8% 10% 35%	2547
August	1st to 10th	Day	11% 5% 2 7% 6% 4 6% 6% 7% 10% 36%	2327
	11th to 20th	Day	13% 6% 2 7% 6% 4 6% 7% 7% 9% 34%	2281
	21st to end	Day	11% 5% 3 6% 6% 3 4 6% 7% 11% 39%	2376
September	1st to 10th	Day	13% 5% 2 5% 5% 3 4 5% 5% 7% 47%	2160
	11th to 20th	Day	13% 6% 3 5% 4 3 4 5% 5% 7% 45%	2025
	21st to end	Day	22% 6% 3 5% 5% 3 4 4 5% 6% 37%	1951
October	1st to 10th	Day	15% 6% 2 4 4 3 3 3 4 6% 51%	1800
	11th to 20th	Day	17% 4 1 4 4 2 3 4 4 7% 51%	1800
	21st to end	Day	13% 6% 2 5% 4 2 4 3 3 6% 52%	1980
November	1st to 10th	Day	12% 4 2 3 3 2 4 3 4 6% 55%	1857
	11th to 20th	Day	15% 5% 2 4 5% 3 4 3 4 6% 50%	1788
	21st to end	Day	15% 4 2 4 4 1 3 3 5% 8% 50%	1520
December	1st to 10th	Day	17% 7% 2 5% 4 3 5% 6% 6% 8% 38%	1520
	11th to 20th	Day	16% 5% 2 4 3 2 3 3 3 6% 53%	1910
	21st to end	Day	19% 5% 3 4 5% 3 5% 4 5% 8% 39%	3039
January	1st to 10th	Night	14% 6% 2 4 4 3 4 4 5% 6% 49%	4109
	11th to 20th	Night	16% 7% 2 4 4 2 3 3 4 6% 48%	4120
	21st to end	Night	22% 6% 3 5% 4 3 3 3 4 5% 42%	4532
February	1st to 10th	Night	14% 6% 2 5% 5% 2 4 4 6% 8% 44%	2470
	11th to 20th	Night	20% 7% 2 5% 4 2 3 4 5% 6% 43%	2403
	21st to end	Night	16% 6% 3 5% 5% 2 5% 4 4 6% 44%	1780
March	1st to 10th	Night	14% 5% 2 4 3 2 4 5% 6% 6% 48%	2090
	11th to 20th	Night	18% 5% 2 4 6% 3 5% 5% 6% 7% 41%	2090
	21st to end	Night	15% 6% 3 5% 5% 3 4 5% 5% 7% 43%	2201
April	1st to 10th	Night	14% 6% 3 4 5% 2 4 5% 5% 6% 46%	1871
	11th to 20th	Night	12% 4 2 5% 4 2 4 4 5% 8% 49%	1775
	21st to end	Night	15% 5% 3 4 6% 2 5% 4 6% 7% 44%	1760
May	1st to 10th	Night	14% 5% 1 5% 5% 3 6% 5% 6% 8% 41%	1620
	11th to 20th	Night	17% 6% 3 6% 5% 3 4 5% 5% 7% 38%	1592
	21st to end	Night	15% 4 2 5% 6% 3 4 5% 5% 9% 42%	1744
June	1st to 10th	Night	10% 3 2 6% 4 4 5% 5% 7% 11% 43%	1495
	11th to 20th	Night	10% 5% 2 6% 6% 3 6% 5% 6% 9% 44%	1440
	21st to end	Night	7% 4 3 3 4 3 5% 7% 7% 11% 44%	1579
July	1st to 10th	Night	9% 5% 3 5% 6% 3 5% 5% 7% 9% 43%	1620
	11th to 20th	Night	5% 4 2 4 5% 4 6% 6% 8% 12% 46%	1620
	21st to end	Night	7% 5% 2 5% 6% 3 7% 6% 8% 10% 40%	1771
August	1st to 10th	Night	11% 6% 3 6% 6% 4 6% 6% 7% 9% 37%	1611
	11th to 20th	Night	11% 7% 3 5% 6% 4 5% 6% 8% 8% 39%	1599
	21st to end	Night	10% 6% 2 6% 6% 4 5% 6% 6% 11% 38%	1980
September	1st to 10th	Night	12% 5% 2 4 5% 3 5% 6% 6% 8% 45%	1800
	11th to 20th	Night	14% 6% 2 4 5% 3 5% 4 6% 7% 45%	1931
	21st to end	Night	22% 7% 3 6% 5% 2 3 3 5% 6% 38%	2007
October	1st to 10th	Night	16% 5% 3 5% 4 2 3 3 4 6% 49%	2160
	11th to 20th	Night	14% 5% 2 4 4 2 4 3 5% 6% 50%	2160
	21st to end	Night	14% 4 1 4 3 2 4 3 4 6% 54%	2376
November	1st to 10th	Night	13% 6% 3 5% 3 2 3 3 3 4 54%	2221
	11th to 20th	Night	13% 4 2 4 3 2 4 4 5% 6% 51%	2384
	21st to end	Night	13% 3 2 4 4 3 5% 4 5% 7% 50%	2660
December	1st to 10th	Night	18% 7% 3 5% 4 3 4 4 4 5% 42%	2660
	11th to 20th	Night	15% 7% 2 4 5% 3 3 3 4 7% 47%	3285
	21st to end	Night	17% 5% 2 5% 5% 3 5% 5% 6% 7% 40%	4596

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	35% 3 8% 29% 19% 6%	2837
	11th to 20th	Day	39% 4 8% 20% 24% 5%	2840
	21st to end	Day	47% 4 6% 23% 17% 3	3124
February	1st to 10th	Day	39% 5% 11% 25% 17% 4	1710
	11th to 20th	Day	41% 4 8% 22% 20% 5%	1672
	21st to end	Day	47% 5% 11% 16% 17% 5%	1669
March	1st to 10th	Day	36% 4 9% 24% 22% 6%	2090
	11th to 20th	Day	41% 7% 9% 18% 18% 7%	2090
	21st to end	Day	46% 5% 9% 20% 16% 4	2200
April	1st to 10th	Day	32% 6% 12% 23% 20% 8%	2088
	11th to 20th	Day	36% 5% 10% 23% 21% 6%	2134
	21st to end	Day	42% 6% 9% 23% 15% 5%	2214
May	1st to 10th	Day	40% 8% 15% 20% 13% 3	2340
	11th to 20th	Day	43% 7% 14% 23% 11% 2	2305
	21st to end	Day	40% 8% 14% 25% 12%	2531
June	1st to 10th	Day	34% 8% 16% 26% 15% 1	2454
	11th to 20th	Day	37% 9% 16% 21% 16% 2	2520
	21st to end	Day	34% 9% 16% 23% 15% 2	2370
July	1st to 10th	Day	39% 9% 15% 20% 15% 3	2275
	11th to 20th	Day	34% 10% 19% 21% 16% 1	2271
	21st to end	Day	40% 9% 14% 22% 14% 1	2405
August	1st to 10th	Day	41% 9% 15% 24% 9% 1	2314
	11th to 20th	Day	43% 10% 15% 21% 10% 1	2281
	21st to end	Day	38% 8% 18% 21% 14% 2	2376
September	1st to 10th	Day	36% 8% 13% 20% 20% 4	2160
	11th to 20th	Day	38% 6% 8% 25% 20% 4	2025
	21st to end	Day	47% 5% 9% 18% 19% 2	1951
October	1st to 10th	Day	36% 3 9% 26% 21% 4	1800
	11th to 20th	Day	35% 4 8% 26% 22% 5%	1800
	21st to end	Day	35% 4 8% 26% 21% 7%	1980
November	1st to 10th	Day	32% 4 9% 23% 27% 5%	1857
	11th to 20th	Day	35% 5% 9% 22% 21% 8%	1788
	21st to end	Day	34% 4 9% 24% 25% 4	1520
December	1st to 10th	Day	43% 6% 11% 20% 17% 4	1520
	11th to 20th	Day	34% 3 8% 26% 21% 8%	1906
	21st to end	Day	43% 4 11% 26% 14% 2	3039
January	1st to 10th	Night	37% 3 8% 24% 23% 5%	4109
	11th to 20th	Night	39% 4 7% 20% 25% 5%	4120
	21st to end	Night	46% 3 6% 23% 16% 6%	4532
February	1st to 10th	Night	37% 5% 11% 24% 19% 3	2470
	11th to 20th	Night	43% 4 8% 19% 19% 7%	2405
	21st to end	Night	41% 4 9% 24% 16% 6%	1780
March	1st to 10th	Night	36% 5% 9% 24% 21% 5%	2090
	11th to 20th	Night	41% 5% 9% 19% 20% 5%	2090
	21st to end	Night	41% 7% 9% 20% 18% 5%	2201
April	1st to 10th	Night	38% 6% 10% 18% 22% 6%	1871
	11th to 20th	Night	34% 5% 11% 22% 22% 7%	1775
	21st to end	Night	38% 6% 11% 23% 17% 4	1760
May	1st to 10th	Night	40% 8% 13% 21% 14% 4	1620
	11th to 20th	Night	45% 7% 12% 22% 11% 3	1593
	21st to end	Night	39% 8% 15% 24% 13% 1	1745
June	1st to 10th	Night	33% 9% 15% 28% 15% 1	1495
	11th to 20th	Night	37% 8% 17% 20% 16% 2	1440
	21st to end	Night	31% 11% 16% 21% 17% 4	1579
July	1st to 10th	Night	36% 10% 17% 18% 15% 5%	1575
	11th to 20th	Night	29% 10% 23% 23% 14% 2	1566
	21st to end	Night	34% 9% 17% 26% 13%	1672
August	1st to 10th	Night	41% 10% 16% 21% 12% 1	1600
	11th to 20th	Night	41% 9% 15% 22% 13% 1	1599
	21st to end	Night	39% 10% 15% 23% 10% 3	1980
September	1st to 10th	Night	37% 8% 13% 20% 17% 5%	1800
	11th to 20th	Night	37% 7% 11% 22% 20% 3	1931
	21st to end	Night	48% 5% 8% 19% 17% 3	2007
October	1st to 10th	Night	37% 4 9% 25% 20% 3	2160
	11th to 20th	Night	35% 5% 7% 25% 22% 5%	2160
	21st to end	Night	32% 3 8% 24% 26% 7%	2376
November	1st to 10th	Night	36% 3 8% 20% 25% 8%	2221
	11th to 20th	Night	33% 4 9% 21% 24% 8%	2384
	21st to end	Night	34% 4 8% 26% 22% 7%	2660
December	1st to 10th	Night	44% 4 8% 23% 17% 4	2660
	11th to 20th	Night	39% 4 8% 21% 21% 7%	3288
	21st to end	Night	41% 5% 11% 22% 18% 2	4596

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	26% 27% 26% 17% 4 1	270
	11th to 20th	Day	30% 21% 34% 14% 1	270
	21st to end	Day	29% 22% 33% 13% 3	297
February	1st to 10th	Day	23% 22% 37% 12% 5%	270
	11th to 20th	Day	40% 22% 29% 6% 3	270
	21st to end	Day	32% 19% 30% 16% 4	348
March	1st to 10th	Day	26% 17% 30% 21% 5%	460
	11th to 20th	Day	20% 23% 33% 19% 5%	460
	21st to end	Day	22% 17% 34% 21% 5% 1	470
April	1st to 10th	Day	22% 20% 28% 22% 8% 1	420
	11th to 20th	Day	19% 15% 29% 21% 12% 3	412
	21st to end	Day	24% 11% 31% 22% 11% 1	420
May	1st to 10th	Day	21% 13% 32% 22% 10% 3	423
	11th to 20th	Day	19% 10% 25% 27% 15% 4	447
	21st to end	Day	20% 3 20% 30% 20% 8%	485
June	1st to 10th	Day	12% 4 25% 31% 21% 6%	450
	11th to 20th	Day	11% 7% 21% 32% 18% 10%	450
	21st to end	Day	10% 4 24% 33% 22% 6%	450
July	1st to 10th	Day	10% 4 15% 28% 30% 13%	445
	11th to 20th	Day	5% 1 14% 36% 30% 13%	444
	21st to end	Day	10% 2 18% 31% 28% 11%	488
August	1st to 10th	Day	14% 6% 16% 26% 26% 13%	446
	11th to 20th	Day	12% 3 15% 28% 28% 14%	439
	21st to end	Day	12% 3 13% 27% 27% 19%	495
September	1st to 10th	Day	14% 4 13% 25% 25% 19%	450
	11th to 20th	Day	15% 4 13% 30% 26% 12%	450
	21st to end	Day	26% 8% 18% 25% 18% 5%	450
October	1st to 10th	Day	22% 6% 17% 31% 18% 6%	450
	11th to 20th	Day	16% 12% 22% 28% 19% 3	450
	21st to end	Day	17% 11% 29% 30% 10% 3	495
November	1st to 10th	Day	18% 7% 30% 27% 13% 3	455
	11th to 20th	Day	20% 15% 27% 25% 11% 2	358
	21st to end	Day	19% 19% 26% 24% 8% 3	180
December	1st to 10th	Day	25% 15% 34% 18% 7% 1	180
	11th to 20th	Day	24% 13% 31% 25% 6% 2	180
	21st to end	Day	27% 14% 33% 18% 6% 2	276
January	1st to 10th	Night	20% 16% 36% 25% 4	760
	11th to 20th	Night	18% 18% 32% 30% 3	760
	21st to end	Night	18% 14% 41% 24% 3	836
February	1st to 10th	Night	16% 15% 38% 27% 3	760
	11th to 20th	Night	25% 17% 37% 20% 1	743
	21st to end	Night	21% 14% 38% 24% 3	628
March	1st to 10th	Night	17% 15% 36% 28% 4	760
	11th to 20th	Night	23% 13% 33% 24% 6% 1	760
	21st to end	Night	18% 12% 35% 28% 5%	801
April	1st to 10th	Night	18% 15% 34% 25% 7%	720
	11th to 20th	Night	14% 13% 32% 29% 12%	711
	21st to end	Night	18% 6% 31% 36% 8%	680
May	1st to 10th	Night	16% 9% 30% 30% 14% 1	540
	11th to 20th	Night	20% 6% 22% 34% 17% 1	531
	21st to end	Night	18% 1 13% 33% 31% 4	584
June	1st to 10th	Night	9% 1 16% 43% 29% 2	415
	11th to 20th	Night	12% 2 16% 40% 27% 3	360
	21st to end	Night	9% 2 12% 45% 29% 3	499
July	1st to 10th	Night	11% 2 10% 37% 36% 5%	525
	11th to 20th	Night	6% 9% 32% 47% 5%	522
	21st to end	Night	8% 1 8% 43% 35% 4	591
August	1st to 10th	Night	13% 2 8% 39% 32% 6%	537
	11th to 20th	Night	14% 2 6% 39% 34% 4	535
	21st to end	Night	13% 2 10% 35% 35% 5%	792
September	1st to 10th	Night	15% 2 8% 32% 36% 7%	720
	11th to 20th	Night	16% 3 11% 34% 32% 5%	720
	21st to end	Night	25% 5% 18% 30% 22% 1	720
October	1st to 10th	Night	19% 4 19% 28% 25% 5%	720
	11th to 20th	Night	16% 8% 23% 34% 17% 2	720
	21st to end	Night	16% 7% 27% 35% 13% 1	792
November	1st to 10th	Night	17% 6% 29% 34% 13% 2	740
	11th to 20th	Night	16% 11% 30% 30% 12% 1	760
	21st to end	Night	14% 11% 31% 33% 10% 1	760
December	1st to 10th	Night	23% 10% 34% 27% 6% 1	760
	11th to 20th	Night	17% 10% 35% 32% 5%	760
	21st to end	Night	21% 12% 33% 31% 4	836

Page generated at 2024-03-19 23:31:05. Version ac07

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