Because the shape of the earth is not a perfect sphere, in which each of the point is on the same distance from the mid point . It is oval in shape so all the points are not on the same distance from the core and thus is varies near equator and the poles.
Height above earths surface is called elevation
they form above earths surface (THIS ANSWER IS NOT CORRECT) They Form BELOW earths surface(:
The epicenter
Infinity
30 feet above sea level and 50 feet above earths surface... science homework these days
Cirrus clouds form far above the Earth's surface, typically at altitudes above 20,000 feet. They are thin and wispy in appearance and are composed of ice crystals.
troposphere
Elevation
no
epicenter
32 kilometers
Erosion, weathering