There has been a lot of talk on the news about temperature inversions, but very little effort to explain what they are. Normally, the higher you rise, the cooler the air gets. Red Lodge may be south of Billings, but it’s over 2,000 feet higher in elevation, so it’s generally cooler. The ski mountain is higher yet, so it’s generally even cooler.
Sometimes, a pocket of cool, dense air will settle into a valley like Red Lodge, and a warm front will move over top of that cool air instead of pushing it out of the way. If that warm air settles over the cool air without disturbing it, we have a situation like the last week of February, where Red Lodge temperatures were hovering just over zero, and it was 26° on Red Lodge Mountain. This is a temperature inversion.
Warm air rises, so why would higher altitudes have cooler temperatures in the first place? First, our atmosphere is heated from the bottom. The sun warms the ground, and the ground warms the air. As warm air attempts to rise, the pressure drops and the air cools.
Inversions like these make for pleasant ski days in Red Lodge, but they can cause serious problems in smoggy areas like Los Angeles or Beijing. Pollution in those cities is trapped near ground level, producing serious health risks.
The Fahrenheit scale (°F) that we use on our thermometers has been replaced with Celsius (°C) in almost every country in the world. Aside from the U.S. and its territories, the only countries still using Fahrenheit are the Bahamas, Belize, and the Cayman Islands.
Developed by Daniel Gabriel Fahrenheit in 1724, our scale originally began with 0° as the freezing point of saturated salt water and 100° as human body temperature. Since neither was precise (nor accurate), it’s now based on 32° and 212° as the freezing and boiling points of water at sea level.