How do I interpret this “sky cover” chart?
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The image below is a screenshot of forecasted sky cover in percentage for various parts of Arizona. Is the sky cover percentage the percentage of each pixel that has cloud, or is it the percentage of a circle with a certain radius where a certain pixel is the center? Not sure how to word it more clearly.
meteorology weather-forecasting
asked yesterday
user6847056user6847056
1064
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add a comment |
$begingroup$
The image below is a screenshot of forecasted sky cover in percentage for various parts of Arizona. Is the sky cover percentage the percentage of each pixel that has cloud, or is it the percentage of a circle with a certain radius where a certain pixel is the center? Not sure how to word it more clearly.
meteorology weather-forecasting
asked yesterday
user6847056user6847056
1064
$endgroup$
add a comment |
$begingroup$
The image below is a screenshot of forecasted sky cover in percentage for various parts of Arizona. Is the sky cover percentage the percentage of each pixel that has cloud, or is it the percentage of a circle with a certain radius where a certain pixel is the center? Not sure how to word it more clearly.
meteorology weather-forecasting
asked yesterday
user6847056user6847056
1064
$endgroup$
The image below is a screenshot of forecasted sky cover in percentage for various parts of Arizona. Is the sky cover percentage the percentage of each pixel that has cloud, or is it the percentage of a circle with a certain radius where a certain pixel is the center? Not sure how to word it more clearly.
meteorology weather-forecasting
meteorology weather-forecasting
asked yesterday
user6847056user6847056
1064
asked yesterday
user6847056user6847056
1064
asked yesterday
user6847056user6847056
1064
asked yesterday
user6847056user6847056
1064
asked yesterday
user6847056user6847056
1064
1064
add a comment |
add a comment |
1 Answer
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The "sky cover" represents the percentage of sky obscured by clouds, as would be visible to an observer at the Earth's surface.
The most direct reference I could find to this quantity was in this archived presentation from the American Meteorological Society's 2014 Annual Meeting: "The United States Federal Meteorological Handbook (FMH) No. 1 defines sky cover as “the amount of the celestial dome hidden by clouds and/or obscurations”.
While I could not locate this particular handbook, there is supporting evidence in the NWS Products and Services Reference Guidebook, specifically Section 9, Tables and Abbreviations: The “sky condition” describes the average percentage of the sky that is covered by opaque clouds (not transparent to light) at a given time, followed by a tabular description of the percentile sky cover forecast interpolated to the forecast image in question:
Slight differences in terminology aside, both of these descriptions equivalently refer to the portion of sky obscured by clouds. For typical weather forecasts (as in the example in question), either would be interpreted as describing the sky as it would be visible to an observer at a given point on the Earth's surface - the visible "celestial dome". See also the definition quoted here from the 2nd edition of the American Meteorology Society's glossary, defining cloud cover as "observed from a particular location," in this case the Earth's surface.
answered yesterday
dplmmrdplmmr
718118
$endgroup$
1
$begingroup$
+1. Is sky cover the same as cloud cover ? Can you clarify that in your answer ?
$endgroup$
– gansub
yesterday
1
$begingroup$
-en.wikipedia.org/wiki/Cloud_cover
$endgroup$
– gansub
yesterday
$begingroup$
Thanks, a good clarification as both refer to the same quantity but exact terminology is variable depending on the source or forecast. Added that and a reference to the definition at the top of the wikipedia article - interestingly, the AMS glossary is my starting point for questions like this but the latest edition omits the mention of any viewing location - still clearly referring to the same thing, though.
$endgroup$
– dplmmr
yesterday
$begingroup$
welcome. I deal with European models mostly and cloud cover is the term used.
$endgroup$
– gansub
yesterday
$begingroup$
According to graphical.weather.gov/definitions/defineSky.html and digital.weather.gov/staticpages/definitions.php, "[Sky Cover] Is the expected amount of opaque clouds (in percent) covering the sky valid for the indicated hour." In observation, a ceilometer would generally "look" at a fixed position directly above its location and a trained observer would generally split the visible sky into eight partitions, or oktas. I suspect a forecast would be more like a ceilometer than an observer.
$endgroup$
– Mike Christianson
23 hours ago
add a comment |
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1 Answer
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$begingroup$
The "sky cover" represents the percentage of sky obscured by clouds, as would be visible to an observer at the Earth's surface.
The most direct reference I could find to this quantity was in this archived presentation from the American Meteorological Society's 2014 Annual Meeting: "The United States Federal Meteorological Handbook (FMH) No. 1 defines sky cover as “the amount of the celestial dome hidden by clouds and/or obscurations”.
While I could not locate this particular handbook, there is supporting evidence in the NWS Products and Services Reference Guidebook, specifically Section 9, Tables and Abbreviations: The “sky condition” describes the average percentage of the sky that is covered by opaque clouds (not transparent to light) at a given time, followed by a tabular description of the percentile sky cover forecast interpolated to the forecast image in question:
Slight differences in terminology aside, both of these descriptions equivalently refer to the portion of sky obscured by clouds. For typical weather forecasts (as in the example in question), either would be interpreted as describing the sky as it would be visible to an observer at a given point on the Earth's surface - the visible "celestial dome". See also the definition quoted here from the 2nd edition of the American Meteorology Society's glossary, defining cloud cover as "observed from a particular location," in this case the Earth's surface.
answered yesterday
dplmmrdplmmr
718118
$endgroup$
1
$begingroup$
+1. Is sky cover the same as cloud cover ? Can you clarify that in your answer ?
$endgroup$
– gansub
yesterday
1
$begingroup$
-en.wikipedia.org/wiki/Cloud_cover
$endgroup$
– gansub
yesterday
$begingroup$
Thanks, a good clarification as both refer to the same quantity but exact terminology is variable depending on the source or forecast. Added that and a reference to the definition at the top of the wikipedia article - interestingly, the AMS glossary is my starting point for questions like this but the latest edition omits the mention of any viewing location - still clearly referring to the same thing, though.
$endgroup$
– dplmmr
yesterday
$begingroup$
welcome. I deal with European models mostly and cloud cover is the term used.
$endgroup$
– gansub
yesterday
$begingroup$
According to graphical.weather.gov/definitions/defineSky.html and digital.weather.gov/staticpages/definitions.php, "[Sky Cover] Is the expected amount of opaque clouds (in percent) covering the sky valid for the indicated hour." In observation, a ceilometer would generally "look" at a fixed position directly above its location and a trained observer would generally split the visible sky into eight partitions, or oktas. I suspect a forecast would be more like a ceilometer than an observer.
$endgroup$
– Mike Christianson
23 hours ago
add a comment |
$begingroup$
The "sky cover" represents the percentage of sky obscured by clouds, as would be visible to an observer at the Earth's surface.
The most direct reference I could find to this quantity was in this archived presentation from the American Meteorological Society's 2014 Annual Meeting: "The United States Federal Meteorological Handbook (FMH) No. 1 defines sky cover as “the amount of the celestial dome hidden by clouds and/or obscurations”.
While I could not locate this particular handbook, there is supporting evidence in the NWS Products and Services Reference Guidebook, specifically Section 9, Tables and Abbreviations: The “sky condition” describes the average percentage of the sky that is covered by opaque clouds (not transparent to light) at a given time, followed by a tabular description of the percentile sky cover forecast interpolated to the forecast image in question:
Slight differences in terminology aside, both of these descriptions equivalently refer to the portion of sky obscured by clouds. For typical weather forecasts (as in the example in question), either would be interpreted as describing the sky as it would be visible to an observer at a given point on the Earth's surface - the visible "celestial dome". See also the definition quoted here from the 2nd edition of the American Meteorology Society's glossary, defining cloud cover as "observed from a particular location," in this case the Earth's surface.
answered yesterday
dplmmrdplmmr
718118
$endgroup$
1
$begingroup$
+1. Is sky cover the same as cloud cover ? Can you clarify that in your answer ?
$endgroup$
– gansub
yesterday
1
$begingroup$
-en.wikipedia.org/wiki/Cloud_cover
$endgroup$
– gansub
yesterday
$begingroup$
Thanks, a good clarification as both refer to the same quantity but exact terminology is variable depending on the source or forecast. Added that and a reference to the definition at the top of the wikipedia article - interestingly, the AMS glossary is my starting point for questions like this but the latest edition omits the mention of any viewing location - still clearly referring to the same thing, though.
$endgroup$
– dplmmr
yesterday
$begingroup$
welcome. I deal with European models mostly and cloud cover is the term used.
$endgroup$
– gansub
yesterday
$begingroup$
According to graphical.weather.gov/definitions/defineSky.html and digital.weather.gov/staticpages/definitions.php, "[Sky Cover] Is the expected amount of opaque clouds (in percent) covering the sky valid for the indicated hour." In observation, a ceilometer would generally "look" at a fixed position directly above its location and a trained observer would generally split the visible sky into eight partitions, or oktas. I suspect a forecast would be more like a ceilometer than an observer.
$endgroup$
– Mike Christianson
23 hours ago
add a comment |
$begingroup$
The "sky cover" represents the percentage of sky obscured by clouds, as would be visible to an observer at the Earth's surface.
The most direct reference I could find to this quantity was in this archived presentation from the American Meteorological Society's 2014 Annual Meeting: "The United States Federal Meteorological Handbook (FMH) No. 1 defines sky cover as “the amount of the celestial dome hidden by clouds and/or obscurations”.
While I could not locate this particular handbook, there is supporting evidence in the NWS Products and Services Reference Guidebook, specifically Section 9, Tables and Abbreviations: The “sky condition” describes the average percentage of the sky that is covered by opaque clouds (not transparent to light) at a given time, followed by a tabular description of the percentile sky cover forecast interpolated to the forecast image in question:
Slight differences in terminology aside, both of these descriptions equivalently refer to the portion of sky obscured by clouds. For typical weather forecasts (as in the example in question), either would be interpreted as describing the sky as it would be visible to an observer at a given point on the Earth's surface - the visible "celestial dome". See also the definition quoted here from the 2nd edition of the American Meteorology Society's glossary, defining cloud cover as "observed from a particular location," in this case the Earth's surface.
answered yesterday
dplmmrdplmmr
718118
$endgroup$
The "sky cover" represents the percentage of sky obscured by clouds, as would be visible to an observer at the Earth's surface.
The most direct reference I could find to this quantity was in this archived presentation from the American Meteorological Society's 2014 Annual Meeting: "The United States Federal Meteorological Handbook (FMH) No. 1 defines sky cover as “the amount of the celestial dome hidden by clouds and/or obscurations”.
While I could not locate this particular handbook, there is supporting evidence in the NWS Products and Services Reference Guidebook, specifically Section 9, Tables and Abbreviations: The “sky condition” describes the average percentage of the sky that is covered by opaque clouds (not transparent to light) at a given time, followed by a tabular description of the percentile sky cover forecast interpolated to the forecast image in question:
Slight differences in terminology aside, both of these descriptions equivalently refer to the portion of sky obscured by clouds. For typical weather forecasts (as in the example in question), either would be interpreted as describing the sky as it would be visible to an observer at a given point on the Earth's surface - the visible "celestial dome". See also the definition quoted here from the 2nd edition of the American Meteorology Society's glossary, defining cloud cover as "observed from a particular location," in this case the Earth's surface.
answered yesterday
dplmmrdplmmr
718118
edited yesterday
answered yesterday
dplmmrdplmmr
718118
answered yesterday
dplmmrdplmmr
718118
answered yesterday
dplmmrdplmmr
718118
718118
1
$begingroup$
+1. Is sky cover the same as cloud cover ? Can you clarify that in your answer ?
$endgroup$
– gansub
yesterday
1
$begingroup$
-en.wikipedia.org/wiki/Cloud_cover
$endgroup$
– gansub
yesterday
$begingroup$
Thanks, a good clarification as both refer to the same quantity but exact terminology is variable depending on the source or forecast. Added that and a reference to the definition at the top of the wikipedia article - interestingly, the AMS glossary is my starting point for questions like this but the latest edition omits the mention of any viewing location - still clearly referring to the same thing, though.
$endgroup$
– dplmmr
yesterday
$begingroup$
welcome. I deal with European models mostly and cloud cover is the term used.
$endgroup$
– gansub
yesterday
$begingroup$
According to graphical.weather.gov/definitions/defineSky.html and digital.weather.gov/staticpages/definitions.php, "[Sky Cover] Is the expected amount of opaque clouds (in percent) covering the sky valid for the indicated hour." In observation, a ceilometer would generally "look" at a fixed position directly above its location and a trained observer would generally split the visible sky into eight partitions, or oktas. I suspect a forecast would be more like a ceilometer than an observer.
$endgroup$
– Mike Christianson
23 hours ago
add a comment |
1
$begingroup$
+1. Is sky cover the same as cloud cover ? Can you clarify that in your answer ?
$endgroup$
– gansub
yesterday
1
$begingroup$
-en.wikipedia.org/wiki/Cloud_cover
$endgroup$
– gansub
yesterday
$begingroup$
Thanks, a good clarification as both refer to the same quantity but exact terminology is variable depending on the source or forecast. Added that and a reference to the definition at the top of the wikipedia article - interestingly, the AMS glossary is my starting point for questions like this but the latest edition omits the mention of any viewing location - still clearly referring to the same thing, though.
$endgroup$
– dplmmr
yesterday
$begingroup$
welcome. I deal with European models mostly and cloud cover is the term used.
$endgroup$
– gansub
yesterday
$begingroup$
According to graphical.weather.gov/definitions/defineSky.html and digital.weather.gov/staticpages/definitions.php, "[Sky Cover] Is the expected amount of opaque clouds (in percent) covering the sky valid for the indicated hour." In observation, a ceilometer would generally "look" at a fixed position directly above its location and a trained observer would generally split the visible sky into eight partitions, or oktas. I suspect a forecast would be more like a ceilometer than an observer.
$endgroup$
– Mike Christianson
23 hours ago
1
1
$begingroup$
+1. Is sky cover the same as cloud cover ? Can you clarify that in your answer ?
$endgroup$
– gansub
yesterday
$begingroup$
+1. Is sky cover the same as cloud cover ? Can you clarify that in your answer ?
$endgroup$
– gansub
yesterday
1
1
$begingroup$
-en.wikipedia.org/wiki/Cloud_cover
$endgroup$
– gansub
yesterday
$begingroup$
-en.wikipedia.org/wiki/Cloud_cover
$endgroup$
– gansub
yesterday
$begingroup$
Thanks, a good clarification as both refer to the same quantity but exact terminology is variable depending on the source or forecast. Added that and a reference to the definition at the top of the wikipedia article - interestingly, the AMS glossary is my starting point for questions like this but the latest edition omits the mention of any viewing location - still clearly referring to the same thing, though.
$endgroup$
– dplmmr
yesterday
$begingroup$
Thanks, a good clarification as both refer to the same quantity but exact terminology is variable depending on the source or forecast. Added that and a reference to the definition at the top of the wikipedia article - interestingly, the AMS glossary is my starting point for questions like this but the latest edition omits the mention of any viewing location - still clearly referring to the same thing, though.
$endgroup$
– dplmmr
yesterday
$begingroup$
welcome. I deal with European models mostly and cloud cover is the term used.
$endgroup$
– gansub
yesterday
$begingroup$
welcome. I deal with European models mostly and cloud cover is the term used.
$endgroup$
– gansub
yesterday
$begingroup$
According to graphical.weather.gov/definitions/defineSky.html and digital.weather.gov/staticpages/definitions.php, "[Sky Cover] Is the expected amount of opaque clouds (in percent) covering the sky valid for the indicated hour." In observation, a ceilometer would generally "look" at a fixed position directly above its location and a trained observer would generally split the visible sky into eight partitions, or oktas. I suspect a forecast would be more like a ceilometer than an observer.
$endgroup$
– Mike Christianson
23 hours ago
$begingroup$
According to graphical.weather.gov/definitions/defineSky.html and digital.weather.gov/staticpages/definitions.php, "[Sky Cover] Is the expected amount of opaque clouds (in percent) covering the sky valid for the indicated hour." In observation, a ceilometer would generally "look" at a fixed position directly above its location and a trained observer would generally split the visible sky into eight partitions, or oktas. I suspect a forecast would be more like a ceilometer than an observer.
$endgroup$
– Mike Christianson
23 hours ago
add a comment |
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