KML doesn’t have the circle object built in, a circle can be made by line or polygon object. With GeoDestination function, a perfect circle can be created.
Polygon@Table[GeoDestination[GeoPosition[{39.17, -86.52 }], {5000, a}], {a, 0, 360, 10}][[All, 1, {2, 1}]]
This line will generate a 36-sides polygon centered at 39.17, –86.52 with 5000 meters radius. Then export it to kml, you probably has to manually modify the kml file to set up the color styles.
Here is an example, we use the radius to represent the vertical motion, 1 cm motion = 5000 meters on the ground.
