Green Sky

A coastal glider field on a salt flat, and the afternoon a supercell crosses it.

The film opens hot and bone dry: cracked salt crust an inch from the lens, an 1,800-metre concrete strip, a windsock, three sailplanes working the lift, and a dark bar on the eastern horizon that is still five kilometres out. Over the next minute the cell arrives and takes the whole sky. The light goes out of the world, the air turns the flat bruised green that comes before hail, rain crosses the pan as a visible wall, the field floods, and the only bright thing left is the lightning going off inside the cloud mass. Then the cell moves off east, the low sun comes in underneath it from the west, and a full rainbow stands over the departing storm with its foot in the flooded field — and a second one lying in the water.

Eighteen composed set-ups. Two minutes. Nobody plays it; it is watched.

What to look for

The sky is a volume, not a backdrop. The storm deck is a compute-raymarched cloud volume re-authored every frame. You can fly a glider into it, stand under it and watch it scroll overhead lobed and veined, and climb six kilometres above it to look down on the tops.

The lightning is a light, not a sprite. Each discharge drives the scene's directional light and the cloud volume's own sun at the same time, so a strike lights the field, the flooded pan and the inside of the cloud together — and the camera stops down about a stop while it happens, the way a real exposure would. In one shot the flash arrives twice: once in the sky, once in the water.

The ground changes state over the runtime. The salt pan goes from dry polygonal crust, through a wetness front you can watch cross the frame behind the rain curtain, to forty centimetres of standing water that reflects the storm and then the rainbow. The last shot reuses the first shot's exact station, lens and 28 cm eye height — same ground, different world.

The rainbow is a real spectral surface, primary and secondary, with a third arc lying reflected in the flood.

Everything else is particles: salt drift streaming over the crust, the rain curtain crossing the pan, rain, drop rings, spray, hail bouncing off wet concrete, mist, and vapour off a wingtip.

Under all of it, a five-cue score and the sound of the place — wind, dry drift, the curtain arriving and leaving, hail, an airframe, and thunder that reaches you a distance-over-343-metres-per-second after its own flash.