In Antarctica (at least in the USAP stations, like McMurdo), weather is categorized into 1 of 3 “weather conditions” based on the “wind chill” temperature, visibility, and how much wind there is. The “wind chill” temperature basically measures how cold it actually feels on the exposed skin due to the blowing wind. Since wind can advect (or transport) heat away as it moves through the atmosphere, stronger wind has the ability to lower the temperature significantly by carrying the heat away from the body, thus making it feel much much colder than it actually is. You can always get 2 temperature measurements: atmospheric temperature (the temperature of the air if the wind wasn’t blowing), and wind chill temperature, and it’s the wind chilltemperature that really matters. The National Weather Service has this nice little chart that might put things into perspective a little better:
The weather folks here on station are continuously monitoring the weather and paying attention to these three factors (wind chill temperature, visibility, and wind), and will designate a “weather condition” accordingly and will update the condition as needed:
Condition 1 (or “Con1”) is the worst condition: it is designated condition 1 when one of these three factors is sustained for more than 1 minute: a) winds are >63 mph, b) visibility is <100 ft, or c) wind chill temperature is < –100°F. You are not allowed to leave your building (wherever you happen to be) under any circumstances during Con1. The entire station will receive alerts if it is expected for the weather to turn to Con1. This is the only weather alert that we receive (for the other conditions it is our responsibility to check the weather updates on station).
Condition 2 (“Con2”) is a little bit nicer, designated when a) winds are 55-63 mph, b) visibility is <0.25 miles, or c) wind chill is –75 to –100 °F, sustained for > 1min. You are allowed to be outside during Con2, and move between buildings on station, but you aren’t really supposed to be out for much, you can’t drive vehicles, and you are not allowed to leave the station for any reason.
Anything better than that (up to the nicest sunny and calm day) is considered Condition 3 (“Con3”; winds <55 mph, visibility >0.25 mi, wind chill > –75°F).
Most of the time it is Con3 on station, since it has a nice wide buffer, but the other day it was designated Con2 very early in the morning and it lasted through the rest of the day. The temperature was about -30°F, with a wind chill of about -60°F!!! It was REALLY cold walking from our dorm to breakfast (and we’re only a couple hundred feet away, door to door), and even going out for lunch (that’s even closer from work than from our dorm!), and the wind was very strong. You often get gusts of wind that, if you are not careful while walking, will definitely knock you on your behind. Sometimes you could hardly see the buildings next door! Toward the end of the day we received an urgent warning at work that the weather would be turning to Con1, so we all had to go home or stay put wherever we were until the weather passed (which could sometimes take days!). We all dropped what we were doing, hurried back to our office to gather anything we wanted to bring home with us, and raced off our of the lab! Luckily, we aren’t too far away from the the galley (that’s what we call the building with the cafeteria on station), so we stopped by to grab food and took it back to the dorm with us. It was exciting to step outside during all of this, by far the coldest and most extreme weather I have ever experienced. Very unique. Here’s a small clip of the wind outside our building, where the wind is actually sheltered, and walking home after work. Also, I’ve added a small demonstration at the end of hot water flashing directly into snow when it is exposed to significantly cold temperatures, like we had here this week. Enjoy!
McMurdo Station Weather – Condition 2