While the meaning of most of the parameters in the exif info is decipherable, I didn't understand what do these two mean? Also, it would be great if someone can explain how are they measured. For an example, check this out: http://www.flickr.com/photos/19224593@N04/5613491852/meta/
Check out the spec (pdf). I think Global Angle is GPSImgDirection (pp.50) and Global Altitude is GPSAltitude (pp.48).
The altitude is the height above the geoid, and can be calculated by a GPS unit that has a good signal from at least four satellites. If the planet were a perfect ellipsoid, this would be the height above mean sea level.
The angle is the bearing in which the camera was facing at the time - this can either be measured with an electronic compass or interpolated from two GPS fixes.
Here is a bit more in-depth Exif information:
The Exif property GPSAltitude holds ONLY the altitude in meters; it goes along with GPSAltitudeRef, which determines if whether it's above / below sea level. A negative value indicates it's below sea level (i.e. Holland or the Dead Sea).
The same is true for GPSImgDirection plus GPSImgDirectionRef, which specifies whether the direction is given as "true" north or "magnetic" north. iPhone 4 owners can see the difference with the Compass app, it allows you to switch between the two different references (I can see a difference of 13 degrees at my location). By default, GPS directions are given in "true" values.