Diamond dust

Yesterday we experienced a phenomenon called diamond dust for the first time this year at Halley. Tiny ice crystals suspended in the air near the surface with a blue sky above, also known as clear sky precipitation, diffract the sunlight causing a range of optical phenomena like halos, sun pillars, and sun dogs, i.e. parhelia. This condition is often accompanied by fog or mist, as was the case yesterday. The effect persisted throughout the night and with an almost full moon, we were witnesses to a spectacular lunar halo illuminating an otherwise starry night sky. During the night the wind picked up resulting in drifting snow at ground level. We awoke to moderate blowing snow the next morning, which soon eased off leaving only strong drifting snow again

I had just launched the daily weather balloon and as I watched it drift at first horizontally off into the distance, suddenly there was a strong gust of wind followed by a complete cessation. Within 5 min the wind direction had changed by 60 degrees, the wind speed dropped by 11 kts along with the temperature, which fell to a chilling -28 degC. I stood in stunned silence, as if someone had changed the weather by the flick of a switch. Shortly afterwards the halo reappeared around the sun and the air seemed to sparkle with diamond dust again

As if this wasn’t enough weather for one day, around the midday weather observation there was another display, this time of iridescent clouds, followed by a brief veil of thick fog, which dissipated within 30 min revealing the stunning scene of the Hinge Zone towards the continent on the horizon with multiple inverted and looming mirages.

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This is the perfect explanation of why I love my job. Every day I have to go outside and therefore I get to see the most beautiful scenery, natural phenomena, and exciting weather that Antarctica has to offer.


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