Early this morning, Solar Impulse took off form Mandalay, headed to toward China—after more than a week spent waiting in Myanmar for weather conditions to improve for flight.

Expected to be one of the most difficult legs of the airplane's round-the-world journey, this part of the trip will see cabin temperatures drop to -20 degrees Celsius as the aircraft passes over the mountains in the Chinese provinces of Yunnan and Sichuan. At points, pilot Bertrand Piccard will have to use additional oxygen in the unpressurized craft. The route, which should see the airplane tracel around 850 miles, should take around 18 hours. [Solar Impulse, PhysOrg]