How to calculate how long an arc second is for a given long/lat?

Question

The title says it all, really. I am wondering what area is covered by a dataset which is one arc second wide.

Thanks,

Rob

Answer 1

You might want to check out this page. Essentially, one degree longitude = 111km * cos(latitude)

Answer 2

At sea level at the equator:

second of angle is one sixtieth of this amount: about 30 meters or 100 feet.

However:

Arc-seconds of latitude remain nearly constant, while arc-seconds of longitude decrease in a trigonometric cosine-based fashion as one moves toward the earth's poles.

Arc seconds aren't really a great way to measure distance. Is there no possibility of using a ruler tool in your GIS or any kind of distance function?

Sources:

http://en.wikipedia.org/wiki/Arc_minute

http://www.esri.com/news/arcuser/0400/wdside.html