Every square is different - depends where the square is in the world.

http://www.arrl.org/locate/gridinfo.html

Simon Brown, HB9DRV

----- Original Message ----- From: "Frank A Cahoy" k0blt@juno.com

A friend and I were discussing the actual physical size of a grid square in kilometers and or miles and we cannot come up with anything positive. Can anyone reading this provide us with those actual numbers? No real argument involved. Just a matter of curiosity..... Thank you in advance...

The area of a grid square is not uniform, it depends on your latitude. The "height" of a square formed by latitude and longitude lines is simply the difference in latitude, in degrees times 60 nautical miles. However the length of a segment of a latitude line between to longitudes in nautical miles is approximately the difference in longitudes times 60 times the cosine of the latitude. Only at the equator, latitude equals zero degrees, is length of a degree of latitude and a degree of longitude equal. The area of grid squares decreases as you move north or south away from the equator.

John WA4WDL

----- Original Message ----- From: "Frank A Cahoy" k0blt@juno.com To: amsat-bb@amsat.org Sent: Sunday, July 01, 2007 12:07 PM Subject: [amsat-bb] Grid Square..Physical Size??

Hello All,

A friend and I were discussing the actual physical size of a grid square in kilometers and or miles and we cannot come up with anything positive. Can anyone reading this provide us with those actual numbers? No real argument involved. Just a matter of curiosity..... Thank you in advance...

73 Frank, K0BLT _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

~69.2 miles N-S, but E-W depends on the latitude. The E-W distance gets less as you head towards the poles as the longitude lines converge, so the size of the square changes.

73, Drew KO4MA

----- Original Message ----- From: "Frank A Cahoy" k0blt@juno.com To: amsat-bb@amsat.org Sent: Sunday, July 01, 2007 12:07 PM Subject: [amsat-bb] Grid Square..Physical Size??

Hello All,

A friend and I were discussing the actual physical size of a grid square in kilometers and or miles and we cannot come up with anything positive. Can anyone reading this provide us with those actual numbers? No real argument involved. Just a matter of curiosity..... Thank you in advance...

73 Frank, K0BLT _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

Frank A Cahoy k0blt@juno.com asked

A friend and I were discussing the actual physical size of a grid square in kilometers and or miles and we cannot come up with anything positive. Can anyone reading this provide us with those actual numbers? No real argument involved. Just a matter of curiosity..... Thank you in advance...

1 degree of latitude = 60 minutes = 60 nautical miles (by definition)

1 nautical mile = 1.852 kilometers (by definition)

1 degree of latitude = 60 * 1.852 = 111.12 km

1 degree of longitude = 60 * 1.852 * cos(latitude) kilometers

At the equator, a grid square is approximately 222 by 111 kilometers.

At 60 degrees north a grid square is approximately square, because cos(60) = 0.5

If you want to bore people at parties, geometry on a sphere, with great circles for lines, is an example of a Riemannian geometry, where (among other things) the sum of the angles in a triangle always exceeds 180 degrees.

Laura Halliday VE7LDH "Que les nuages soient notre Grid: CN89mg pied a terre..." ICBM: 49 16.05 N 122 56.92 W - Hospital/Shafte

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