So, I took this a few days ago from behind my house. And you can’t really see, but there’s a thin layer of wood smoke over the West shore of the lake (there must be a lot of vacation homes owned, or rented by people from warmer climes over there because it wasn’t that cold that day). There was a very clear delineation between the smoke and the clear air above it, and why it was so flat at the top of the smoke. Anyone correct me if I’m wrong, but I’m pretty sure the cause of that was this …
This occurs because of a phenomenon called a temperature inversion. Usually, air decreases in temperature as it rises, and cooler air is less dense, so it rises. So polluted air near the ground in a city is gets warmed (because the ground is warmer than the air) and it rises. As it rises, it cools off and tends to keep rising up into the upper atmosphere. A temperature inversion occurs when air near the ground is relatively cool, and there is a layer of warmer air above it. That upper layer of warm air keeps the cooler air from rising, and traps all of the pollution in the cooler, lower layer. So for example in LA, you tend to have relatively cool air near the ground because of sea breezes from the nearby ocean. But you also tend to have warmer air coming over the mountains from the desert (think of the warm Sundowners and Santa Ana winds as extreme examples of this). That layer of warm air traps the cool, polluted air in the city. Similar things can happen in deep mountain valleys (like where Mexico City is) because the valley floor gets very cold at night and the cold air then gets trapped in the valley.
And, temperature inversions aren’t exclusive to large cities
To invert something is to turn it upside down from its normal condition. When we talk about a temperature inversion, we are speaking about an atmospheric condition that is upside down from the way things normally are. In a “normal” atmosphere, the temperature decreases the farther up you go from the earth’s surface.
This creates the temperature inversion situation pictured to the right. The effect can be especially pronounced in the winter months when towns like Custer or Hill City can have temperatures near 50 while Rapid City struggles to reach 30 degrees. The sun heats the ground during the day, creating a warm layer of air near the ground. As the warm air rises away from the heated surface, it cools. Sometimes, a layer of air is so cold and dense that it resists the warming effect of the sun and hugs the ground while less dense air above it warms at a faster rate.
What makes the brain tick so fast?
New study sheds light on the workings of brain neurotransmitter receptors
- February 25, 2016
- McGill University
- Surprisingly complex interactions between neurotransmitter receptors and other key proteins help explain the brain’s ability to process information with lightning speed, according to a new study. Scientists combined experimental techniques to examine fast-acting protein macromolecules, known as AMPA receptors, which are a major player in brain signaling.