Arctic Air

I woke up this morning. Coincidentally, four minutes before my alarm would go off. Then I realized I didn't set it. I was feeling lucky that I was up in time for my morning jog. As I was putting my jogging stuff on, I was listening to the radio. The weather report was on.

My area has a northern arctic airflow warning. What does that mean? I understand what a rainfall warning or a snowfall warning is or even a tsunami warning. But I've never heard of a airflow warning. So after my jog, I trotted over to my computer to look that up.

Meteorologists classify frigid Northern Hemisphere air masses as Arctic when they are born north of the Arctic Circle. It is typified by extremely cold temperatures and very little moisture.

In the birth grounds of these air masses, the long, dark winter nights couple with clear skies and surfaces covered with snow and ice to continually chill the air. Little warming heat from the sun alleviates the cold. The surface snow and ice reflect away most of what little sun weakly beams down. To accentuate the lack of incoming heat, snow very effectively radiates away what little heat it has, thus dropping surface air temperatures until they reach the temperature of the high atmosphere.

The air masses build for some time in these frigid cradles, and the more time they spend in their deep-freeze birthing grounds, the cold and drier they become, chilling the air to bitter temperatures, often less than minus 40 ^oC/F. As a result of that extreme cold, arctic air masses have an extremely low water vapour content (absolute humidity). The low water vapour content further permits the loss of heat from the surface and the air above it because water vapour is a very effective greenhouse gas. The lower the water content, the more radiative heat is lost directly to space.

Eventually high-altitude winds catch the air masses and push them outward, usually toward the south and east as huge High pressure systems. This is strange because I'm in the west, not east.



I've seen evidence of this phenomena because all the moisture in the air is gone. It's wicked cold too. Talking to some students, they've commented it is not usual for it to be like this here. That's good to know because I'm freezing my ass off.

The temperature this morning, with windchill was - 18°C. Ouch! It will be like that overnight tonight.

At least it's not snowing.