Australian Weather Calendar: Cover 2020

Cover 2020 Photographer Warren Keelan

The light chaser

Growing up surfing along the New South Wales south coast gave seascape and ocean photographer Warren Keelan a deep understanding of the relationship between the ocean and the weather. ‘In Wollongong, the escarpment plays a role in how storms build up over the coast at certain times of the year, and drop rain in the afternoons,’ he explains. ‘I chase the light in the afternoons for rainbows—at a certain angle you get that refraction and I try to be out in the water when that happens.’ The moment he captured the vivid rainbow featured on the cover of the 2020 Australian Weather Calendar, Warren says the sky had turned very dark and it had just started raining. ‘As the waves were rolling in front of me I tried to compose a shot where the rainbow was coming down and almost touching the top of the water.’ Warren says he’s constantly checking the Bureau’s website for the latest weather, including wind and tide information, and swell direction and height. ‘I used to be more of a landscape photographer, but felt I needed more of a challenge and a different perspective, which being in the ocean certainly gives you.’ These days Warren focuses on capturing what’s he’s feeling and experiencing. 'It could be the spray from a wave, it could be the movement or the light on the water, and how those elements evoke feeling and emotions. Like rainbows, those ephemeral, fleeting moments—just to be there is a real rush.'

The science

Rainbows are optical phenomena that occur when sunlight and rain combine in a specific way. When white sunlight enters a raindrop, it changes direction (refracts) at the boundary of the raindrop. As different wavelengths within the sunlight refract at slightly different angles, the colours spread out and separate. Some of the light bounces off the back of the raindrop (reflection) and as this light comes back out of the raindrop it refracts again, spreading the colours out further. When you look away from the Sun and towards rain, there is an arc of the sky in which the angle between the Sun, raindrops and the observer is 42°. You'll see just the red light reflected from raindrops in that arc. From raindrops a little lower in the sky, where the angle is 41°, you see just green light reflected; and from drops lower again (40°) you see violet light reflected.