Grove City College
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Grove City College clear sky chart from 2005-11-06 to 2024-02-25.

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	17% 12% 5% 8% 6% 3 4 5% 5% 7% 29%	78464
	Night	17% 12% 5% 8% 6% 3 4 4 4 6% 30%	80821
Transparency	Day	55% 6% 11% 17% 10% 1	78181
	Night	56% 6% 10% 17% 10% 1	80623
Seeing	Day	24% 15% 28% 19% 10% 4	13635
	Night	24% 14% 27% 24% 10% 1	23438

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	18% 23% 10% 13% 6% 2 3 3 3 4 16%	2754
	11th to 20th	Day	13% 22% 10% 14% 9% 4 3 3 3 4 15%	2840
	21st to end	Day	25% 19% 11% 12% 9% 3 3 3 2 3 10%	3124
February	1st to 10th	Day	18% 17% 7% 11% 9% 4 4 3 3 4 20%	1710
	11th to 20th	Day	16% 13% 7% 14% 10% 3 5% 3 5% 5% 20%	1663
	21st to end	Day	20% 15% 4 11% 7% 2 4 5% 3 5% 24%	1500
March	1st to 10th	Day	17% 12% 6% 9% 7% 3 4 4 5% 7% 27%	1980
	11th to 20th	Day	19% 14% 5% 8% 6% 3 4 4 4 6% 28%	1980
	21st to end	Day	22% 12% 5% 8% 6% 4 4 4 4 6% 27%	2178
April	1st to 10th	Day	16% 13% 4 7% 5% 3 4 5% 4 7% 31%	2078
	11th to 20th	Day	20% 11% 3 7% 5% 3 4 4 5% 6% 32%	2181
	21st to end	Day	22% 10% 3 7% 5% 2 3 4 4 6% 33%	2340
May	1st to 10th	Day	20% 9% 3 7% 6% 3 5% 6% 6% 6% 28%	2340
	11th to 20th	Day	21% 8% 3 6% 7% 3 5% 6% 5% 6% 30%	2301
	21st to end	Day	13% 6% 3 5% 6% 4 6% 5% 7% 8% 38%	2712
June	1st to 10th	Day	16% 6% 3 6% 7% 3 5% 6% 7% 9% 32%	2520
	11th to 20th	Day	15% 8% 3 6% 6% 4 6% 5% 5% 9% 34%	2520
	21st to end	Day	16% 5% 2 5% 6% 4 6% 5% 6% 9% 37%	2520
July	1st to 10th	Day	11% 6% 3 5% 5% 3 6% 5% 6% 9% 40%	2498
	11th to 20th	Day	12% 6% 3 6% 5% 3 5% 5% 7% 8% 39%	2340
	21st to end	Day	12% 6% 3 6% 5% 4 7% 6% 7% 9% 35%	2547
August	1st to 10th	Day	11% 6% 2 6% 6% 4 6% 7% 7% 10% 35%	2327
	11th to 20th	Day	14% 7% 3 6% 8% 4 6% 7% 6% 9% 32%	2303
	21st to end	Day	12% 5% 3 7% 7% 4 6% 7% 6% 9% 35%	2466
September	1st to 10th	Day	17% 7% 3 5% 4 3 4 4 5% 8% 40%	2160
	11th to 20th	Day	13% 6% 2 5% 5% 3 5% 6% 6% 7% 41%	1990
	21st to end	Day	19% 7% 3 6% 5% 3 4 4 5% 8% 35%	1977
October	1st to 10th	Day	17% 8% 2 6% 7% 3 4 5% 5% 8% 36%	1800
	11th to 20th	Day	21% 9% 4 7% 6% 4 5% 5% 4 5% 31%	1800
	21st to end	Day	26% 10% 5% 6% 5% 3 4 5% 5% 6% 26%	1980
November	1st to 10th	Day	11% 11% 3 7% 6% 4 5% 5% 4 7% 37%	1758
	11th to 20th	Day	18% 15% 4 7% 6% 3 4 4 5% 5% 29%	1555
	21st to end	Day	19% 19% 6% 8% 6% 3 3 5% 4 5% 21%	1520
December	1st to 10th	Day	19% 22% 9% 10% 6% 4 4 4 4 4 14%	1520
	11th to 20th	Day	18% 18% 8% 13% 5% 3 4 4 5% 6% 16%	1910
	21st to end	Day	26% 26% 8% 9% 5% 3 3 2 3 3 12%	2772
January	1st to 10th	Night	16% 22% 11% 14% 7% 3 3 3 3 4 13%	4173
	11th to 20th	Night	16% 19% 10% 16% 7% 4 6% 4 3 4 12%	4120
	21st to end	Night	27% 18% 10% 9% 9% 2 3 3 2 3 13%	4532
February	1st to 10th	Night	19% 14% 7% 11% 9% 4 4 4 3 5% 21%	2470
	11th to 20th	Night	18% 13% 6% 11% 7% 4 5% 4 5% 5% 21%	2403
	21st to end	Night	20% 13% 6% 11% 7% 3 4 4 4 5% 23%	1845
March	1st to 10th	Night	16% 13% 5% 8% 6% 4 4 4 5% 6% 28%	1980
	11th to 20th	Night	20% 11% 4 6% 6% 3 4 3 4 7% 33%	1980
	21st to end	Night	18% 12% 5% 7% 6% 2 5% 4 4 5% 31%	2178
April	1st to 10th	Night	18% 13% 5% 6% 5% 3 4 4 5% 6% 31%	1882
	11th to 20th	Night	18% 9% 3 7% 4 3 5% 5% 4 5% 36%	1743
	21st to end	Night	15% 12% 3 7% 6% 2 4 5% 6% 6% 35%	1620
May	1st to 10th	Night	18% 8% 4 6% 6% 3 5% 5% 5% 7% 33%	1620
	11th to 20th	Night	16% 8% 3 5% 5% 3 5% 4 6% 8% 36%	1592
	21st to end	Night	10% 6% 3 5% 6% 3 4 5% 6% 10% 44%	1563
June	1st to 10th	Night	10% 5% 3 5% 6% 4 5% 5% 7% 7% 44%	1440
	11th to 20th	Night	12% 5% 3 6% 6% 3 5% 5% 5% 8% 43%	1440
	21st to end	Night	11% 5% 2 6% 6% 3 4 5% 5% 9% 43%	1440
July	1st to 10th	Night	8% 5% 3 5% 5% 3 5% 6% 6% 6% 47%	1458
	11th to 20th	Night	9% 4 2 5% 5% 3 4 5% 6% 9% 48%	1620
	21st to end	Night	10% 5% 3 5% 5% 3 5% 7% 7% 8% 42%	1771
August	1st to 10th	Night	8% 6% 2 5% 5% 3 4 5% 6% 8% 48%	1611
	11th to 20th	Night	11% 6% 3 5% 5% 3 5% 5% 5% 8% 44%	1598
	21st to end	Night	11% 5% 2 4 4 3 5% 5% 6% 9% 46%	1872
September	1st to 10th	Night	13% 5% 3 6% 5% 3 5% 4 5% 7% 46%	1800
	11th to 20th	Night	11% 4 2 4 3 2 4 4 5% 8% 51%	1966
	21st to end	Night	17% 7% 2 6% 5% 3 5% 4 5% 6% 40%	1981
October	1st to 10th	Night	16% 7% 2 5% 5% 3 4 4 4 6% 43%	2160
	11th to 20th	Night	18% 7% 2 7% 5% 3 5% 5% 5% 7% 36%	2160
	21st to end	Night	26% 10% 2 6% 4 3 4 4 4 5% 31%	2376
November	1st to 10th	Night	14% 10% 3 5% 4 3 4 4 5% 7% 40%	2316
	11th to 20th	Night	17% 14% 5% 8% 6% 3 4 4 5% 7% 27%	2622
	21st to end	Night	19% 15% 5% 7% 6% 3 5% 4 4 6% 26%	2660
December	1st to 10th	Night	22% 17% 9% 11% 7% 2 4 3 4 4 16%	2660
	11th to 20th	Night	19% 19% 7% 10% 7% 3 4 3 3 5% 19%	3285
	21st to end	Night	25% 22% 8% 9% 6% 3 4 4 4 4 11%	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	74% 4 8% 9% 5%	2755
	11th to 20th	Day	75% 3 8% 11% 3	2840
	21st to end	Day	82% 4 7% 6% 2	3124
February	1st to 10th	Day	70% 4 8% 12% 6%	1710
	11th to 20th	Day	68% 4 8% 13% 7%	1672
	21st to end	Day	64% 5% 9% 14% 7% 2	1500
March	1st to 10th	Day	57% 5% 12% 18% 7%	1980
	11th to 20th	Day	58% 5% 9% 17% 9% 2	1980
	21st to end	Day	60% 4 7% 17% 11% 1	2178
April	1st to 10th	Day	53% 6% 11% 17% 12% 1	2078
	11th to 20th	Day	52% 5% 10% 17% 13% 2	2181
	21st to end	Day	54% 4 9% 19% 11% 2	2340
May	1st to 10th	Day	54% 7% 11% 18% 9% 2	2340
	11th to 20th	Day	54% 7% 10% 15% 12% 2	2305
	21st to end	Day	42% 9% 14% 22% 11% 2	2712
June	1st to 10th	Day	47% 8% 12% 21% 11% 1	2520
	11th to 20th	Day	47% 8% 12% 20% 12% 1	2520
	21st to end	Day	42% 8% 10% 26% 12% 1	2520
July	1st to 10th	Day	40% 8% 12% 23% 14% 3	2429
	11th to 20th	Day	41% 7% 13% 24% 15% 1	2271
	21st to end	Day	42% 8% 14% 20% 15% 1	2405
August	1st to 10th	Day	41% 9% 14% 27% 9% 1	2314
	11th to 20th	Day	46% 10% 14% 19% 9% 1	2303
	21st to end	Day	43% 9% 12% 20% 14% 2	2466
September	1st to 10th	Day	43% 6% 12% 20% 15% 3	2160
	11th to 20th	Day	39% 8% 13% 24% 15% 1	1990
	21st to end	Day	47% 8% 11% 22% 12%	1977
October	1st to 10th	Day	46% 7% 13% 19% 15% 1	1800
	11th to 20th	Day	56% 5% 11% 20% 9%	1800
	21st to end	Day	58% 5% 12% 14% 9% 1	1980
November	1st to 10th	Day	46% 6% 12% 18% 16% 2	1758
	11th to 20th	Day	57% 5% 11% 18% 7% 2	1555
	21st to end	Day	65% 5% 9% 15% 5% 1	1520
December	1st to 10th	Day	73% 5% 10% 9% 3	1520
	11th to 20th	Day	71% 4 9% 13% 3	1906
	21st to end	Day	79% 3 9% 8% 1	2772
January	1st to 10th	Night	76% 4 8% 10% 2	4173
	11th to 20th	Night	77% 5% 8% 9% 2	4120
	21st to end	Night	79% 3 6% 9% 3	4532
February	1st to 10th	Night	67% 4 8% 15% 5%	2470
	11th to 20th	Night	65% 4 9% 15% 6%	2405
	21st to end	Night	63% 5% 8% 15% 9% 1	1845
March	1st to 10th	Night	57% 6% 9% 18% 9% 1	1980
	11th to 20th	Night	54% 4 12% 19% 10% 1	1980
	21st to end	Night	56% 4 8% 17% 13% 2	2178
April	1st to 10th	Night	54% 5% 10% 18% 12% 1	1882
	11th to 20th	Night	49% 6% 10% 17% 15% 3	1743
	21st to end	Night	48% 6% 10% 21% 11% 3	1620
May	1st to 10th	Night	50% 7% 9% 18% 13% 3	1620
	11th to 20th	Night	46% 7% 10% 19% 15% 2	1593
	21st to end	Night	35% 7% 15% 27% 14% 2	1564
June	1st to 10th	Night	38% 7% 13% 26% 15% 1	1440
	11th to 20th	Night	39% 8% 12% 22% 16% 2	1440
	21st to end	Night	38% 7% 13% 24% 17%	1440
July	1st to 10th	Night	37% 8% 10% 23% 19% 3	1417
	11th to 20th	Night	31% 9% 14% 25% 19% 2	1566
	21st to end	Night	37% 9% 14% 22% 16% 2	1672
August	1st to 10th	Night	33% 7% 15% 28% 16% 1	1600
	11th to 20th	Night	37% 8% 14% 26% 14% 1	1598
	21st to end	Night	33% 8% 15% 25% 16% 3	1872
September	1st to 10th	Night	37% 5% 12% 24% 18% 4	1800
	11th to 20th	Night	31% 6% 13% 27% 22% 1	1966
	21st to end	Night	46% 5% 12% 20% 17% 1	1981
October	1st to 10th	Night	41% 7% 13% 23% 15% 2	2160
	11th to 20th	Night	46% 6% 13% 21% 11% 1	2160
	21st to end	Night	55% 6% 11% 17% 10% 2	2376
November	1st to 10th	Night	42% 5% 13% 22% 14% 3	2316
	11th to 20th	Night	57% 5% 9% 18% 8% 3	2622
	21st to end	Night	60% 6% 10% 18% 5% 1	2660
December	1st to 10th	Night	72% 5% 9% 10% 4	2660
	11th to 20th	Night	69% 4 10% 14% 3	3288
	21st to end	Night	77% 5% 9% 8% 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	33% 28% 27% 10% 4	249
	11th to 20th	Day	34% 28% 28% 7% 2 1	270
	21st to end	Day	33% 28% 29% 9% 2	297
February	1st to 10th	Day	33% 26% 33% 7%	270
	11th to 20th	Day	36% 29% 28% 6% 1	270
	21st to end	Day	40% 25% 28% 7%	228
March	1st to 10th	Day	34% 21% 31% 12% 2	420
	11th to 20th	Day	34% 18% 31% 11% 3 1	420
	21st to end	Day	35% 22% 25% 15% 3	462
April	1st to 10th	Day	29% 23% 25% 15% 7% 1	420
	11th to 20th	Day	28% 20% 26% 17% 6% 3	412
	21st to end	Day	32% 18% 30% 14% 5% 2	420
May	1st to 10th	Day	30% 18% 27% 17% 6% 2	423
	11th to 20th	Day	24% 12% 33% 18% 9% 3	447
	21st to end	Day	17% 11% 28% 24% 13% 7%	485
June	1st to 10th	Day	18% 10% 34% 25% 9% 3	450
	11th to 20th	Day	21% 13% 24% 26% 13% 3	450
	21st to end	Day	16% 13% 31% 26% 10% 3	450
July	1st to 10th	Day	12% 7% 22% 28% 21% 9%	445
	11th to 20th	Day	14% 7% 27% 29% 17% 7%	444
	21st to end	Day	14% 6% 30% 27% 16% 7%	488
August	1st to 10th	Day	12% 6% 25% 28% 21% 8%	446
	11th to 20th	Day	17% 6% 23% 27% 17% 9%	439
	21st to end	Day	11% 6% 26% 31% 17% 9%	495
September	1st to 10th	Day	17% 6% 26% 26% 18% 7%	450
	11th to 20th	Day	14% 6% 23% 26% 21% 10%	450
	21st to end	Day	22% 13% 26% 22% 13% 4	450
October	1st to 10th	Day	18% 11% 29% 22% 16% 4	450
	11th to 20th	Day	26% 18% 32% 16% 8% 1	450
	21st to end	Day	34% 15% 29% 17% 5%	495
November	1st to 10th	Day	22% 22% 29% 16% 9% 2	356
	11th to 20th	Day	32% 23% 28% 11% 5% 2	196
	21st to end	Day	26% 26% 37% 10% 1	180
December	1st to 10th	Day	37% 28% 25% 6% 2 2	180
	11th to 20th	Day	37% 22% 30% 9% 2	180
	21st to end	Day	35% 27% 29% 9% 1	198
January	1st to 10th	Night	32% 21% 32% 12% 2	760
	11th to 20th	Night	34% 21% 29% 14% 2	760
	21st to end	Night	28% 23% 31% 16% 2	836
February	1st to 10th	Night	32% 19% 28% 20% 2	760
	11th to 20th	Night	29% 22% 35% 13% 1	743
	21st to end	Night	32% 21% 29% 15% 2	611
March	1st to 10th	Night	27% 19% 33% 18% 3	720
	11th to 20th	Night	31% 17% 27% 18% 7%	720
	21st to end	Night	27% 16% 34% 19% 4 1	792
April	1st to 10th	Night	28% 15% 30% 20% 7%	720
	11th to 20th	Night	25% 15% 32% 19% 9% 1	679
	21st to end	Night	22% 12% 35% 25% 5% 1	540
May	1st to 10th	Night	23% 10% 24% 33% 10% 1	540
	11th to 20th	Night	21% 8% 28% 34% 9% 1	531
	21st to end	Night	9% 5% 29% 32% 21% 2	403
June	1st to 10th	Night	11% 3 30% 39% 16%	360
	11th to 20th	Night	15% 6% 25% 39% 15%	360
	21st to end	Night	11% 6% 27% 36% 19% 1	360
July	1st to 10th	Night	8% 2 21% 41% 23% 4	367
	11th to 20th	Night	10% 4 19% 36% 26% 4	522
	21st to end	Night	13% 3 13% 43% 27% 1	591
August	1st to 10th	Night	12% 3 16% 40% 26% 3	537
	11th to 20th	Night	14% 3 13% 40% 26% 4	534
	21st to end	Night	12% 4 21% 32% 26% 5%	684
September	1st to 10th	Night	15% 4 22% 31% 24% 3	720
	11th to 20th	Night	13% 5% 19% 33% 25% 5%	720
	21st to end	Night	20% 10% 23% 25% 18% 4	720
October	1st to 10th	Night	18% 9% 24% 28% 18% 3	720
	11th to 20th	Night	22% 13% 31% 25% 7% 1	720
	21st to end	Night	31% 13% 29% 23% 4	792
November	1st to 10th	Night	19% 13% 29% 28% 10% 1	740
	11th to 20th	Night	29% 18% 27% 19% 6% 1	760
	21st to end	Night	31% 16% 30% 18% 4 1	760
December	1st to 10th	Night	33% 22% 25% 16% 4	760
	11th to 20th	Night	29% 24% 27% 17% 4	760
	21st to end	Night	33% 21% 28% 17% 1	836

Page generated at 2024-02-22 06:05:44. Version ac07

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