what cloud with the maximum altitude of 6000.0 or more belongs to the same classification as cumulonimbus calvus?
(AND meteorology.cloud (AND (JOIN meteorology.cloud.classification (JOIN (R meteorology.cloud.classification) m.0bw1t9)) (le meteorology.cloud.maximum_altitude_m 6000.0^^http://www.w3.org/2001/XMLSchema#float)))