Why is weather so important to Solar Impulse?

The Swiss Solar Impulse 2 plane requires good weather for its around-the-world record attempt: difficult when it comes to long crossings. (SRF/RTS/SolarImpulse/swissinfo.ch)

The plane’s journey so far has shown that the right weather conditions are rare. Wind and cold fronts have, in the past, played havoc with the Swiss solar-powered plane’s attempt to go around the world.  

By the time pilot André Borschberg started the first Pacific crossing from Japan to Hawaii on June 28, the team had waited for nearly two months for a clear weather window.

The problem is that Solar Impulse 2 cannot fly in winds over four knots or 7km/h, so it requires almost perfect conditions. The five days and five nights of good weather needed for the Pacific crossing were almost impossible to guarantee. 

Meteorologists at mission control in Monaco work around the clock to provide detailed weather advice when the plane is in the air.

A good forecast will also be needed for the next leg of its journey, across the Pacific from Hawaii to Phoenix in the United States. The idea is to then hopscotch across the United States and the Atlantic to Europe, before returning to Abu Dhabi. 

If the pilot hits inclement weather on one of the legs, it could mean baling out and ditching the plane.