http://www.airborne.com.au/airnews/?p=2049

William Olive known to his mates and others as Billo has been a
consistent visitor to the Gulf of Carpentaria. The attraction to this remote
area at the top end of Australia has mainly been the incredible wave cloud
phenomena named the “Morning Glory”. The series of roll clouds form when
moisture from onshore sea breezes is evident. The rolling wave can be up to 1000
kms(620mi) long. The wave continues it’s journey inland producing lift in front
of the cloud. This lift allows pilot’s of all sorts of aircraft the opportunity
to “surf” the cloud for miles inland until it finally dissipates. The cloud base
is usually only 100 – 200 metres (330-660 ft) high and moves at speeds up to 60
kms (37mi) per hour.

Billo with his crew Brett Paull XT 582 and Cruze wing was able to climb up to
the cloud and switch off the engine and soar to the world record now at 48.4 Km