Most would fly below 3,000ft, but there is no engineering reason why they couldn't fly at altitudes of up to 80,000ft.
Developed by Ascenta, a Somerset-based designer of solar-powered drones bought by Facebook in March 2014, the drones will be able to fly at altitudes of 60,000 feet for months at a time on solar power.
By the late forties, experimental planes were breaking the speed of sound and flying at altitudes of more than seventy thousand feet.
The S-200 has a range of roughly 186 miles, according to U.S. military documents, and can hit targets flying at altitudes of around 130,000 feet.
When jet airplanes, typically flying at altitudes of 30,000 or 35,000 feet, burn fuel, one of the products of combustion is water vapor.
The most straightforward option, according to the report, would be to develop a vehicle capable of flying at altitudes of 20-25km (about 65,000-80,000 feet), distributing ten tonnes of acid a flight.
While commercial airliners int he 1950's flew at altitudes of up to 30,000 feet, the U-2 soared to more than 60,000 feet and the SR-71 to more than 80,000 feet, or 15 miles, nearly the edge of space.
The aircraft flew at altitudes of 61.0 m in the northern treated area and 91.4 m (because of obstacles such as tall towers and buildings) in the southern treated area (R. Laffey, SYMVCD, unpub. data, D. Markowski, pers. comm).
The 12-metre tall helium-filled balloons fly in the stratosphere at altitudes of between 18km and 25km - twice as high as aeroplanes.
Airplanes flying through large storms at altitudes of about 10,000 metres (33,000 feet) have measured updrafts exceeding 30 metres (98 feet) per second.
Birds have been observed to fly at maximum altitudes of 8,200 metres (27,000 feet), and on Mount Everest jumping spiders have been found at 6,700 metres (22,000 feet).
