Parallel lines of cumulus clouds stream over the Labrador Sea in this satellite image. These cloud streets are formed when cold, dry winds blow across comparatively warm waters. As the air warms and moistens over the open water, it rises until it hits a temperature inversion, which forces it to roll to the side, forming parallel cylinders of rotating air. On the rising side of the cylinder, clouds form while skies remain clear where the air is sinking. The result are these long, parallel cloud bands. (Image credit: J. Stevens; via NASA Earth Observatory)
Tag: temperature inversion
Sunrise Cloudscape
With the low sun angle of dawn, the details of this cloudscape stand out. Captured by an external camera on the International Space Station, this image shows cloud formations over the northwest Atlantic. In the foreground, towering cumuli mark rising plumes of warm, moist air evaporating from the ocean. Beyond those clouds, a flat anvil cloud spreads horizontally after a temperature inversion prevented it from rising any further. (Image credit: NASA; via NASA Earth Observatory)
Bullseye
The Cumbre Vieja volcano in the Canary Islands began erupting in mid-September 2021. This satellite image, captured October 1st, shows a peculiar bullseye-like cloud over the volcano. Hot water vapor and exhaust gases rose rapidly from the erupting volcano until colliding with a drier, warmer air layer at an altitude of 5.3 kilometers. The warm upper layer, known as a temperature inversion, prevented the volcanic gases from rising any further, so they instead spread horizontally. The outflow from the volcano varies and is non-uniform, and its fluctuations generated gravity waves that are visible here as the expanding rings of clouds. (Image credit: L. Dauphin; via NASA Earth Observatory)
Superior Mirage
This photograph of a ship seemingly floating far above the water is not some Photoshop fakery; it’s physics creating the illusion. It’s an example of what’s known as a superior mirage — superior because the mirage appears above the object’s actual location, unlike the mirages you see above the road on a hot day.
In this case, the air layer near the water is cold — colder than the air above it, thanks to a temperature inversion. Cold air is denser and has a higher index of refraction, so light traveling through it gets bent downward. To a far off observer, this downward bend makes objects appear higher in altitude than they actually are. The effect is most common in polar regions, where the right conditions can actually allow images of objects completely below the horizon! (Image credit: D. Morris; via The Guardian; submitted by Alec)
The Great Smog of London
Our atmosphere is active and ever-changing – except when it isn’t. Some areas, including many cities, are prone to what’s known as a temperature inversion, where a layer of cooler air gets trapped underneath a warmer one. Because this means that a dense layer is caught under a less dense one, the situation is stable and – absent other changes in circumstances – will stick around. There are several ways this can happen, including overnight when areas near the ground cool faster than the atmosphere higher up.
When temperature inversions persist, they can trap pollutants and create health hazards. One of the worst of these recorded occurred in December 1952 in London. An anticyclone created a temperature inversion over the city that trapped smoke from coal burned to warm homes and reduced visibility – sometimes even indoors – to only a meter or two. Thousands of people died from the respiratory effects of the five-day smog, and it prompted major efforts to improve emissions and air quality. Temperature inversions cannot be avoided, but the Great Smog of London taught us the necessity of reducing their danger. (Image credit: Getty Images)
The Foggy Grand Canyon
On occasion in the late fall and early winter, the Grand Canyon can fill with clouds of fog. This occurs when a layer of warm air traps cold, moist air inside the canyon, creating what’s known as a temperature inversion. The trapped air’s moisture condenses into fog, creating the appearance of a cloud sea lapping at the canyon walls. Such inversions often proceed a big snowstorm, as shown in this video. (Video and image credit: H. Mehmedinovic / SKYGLOWPROJECT; via Gizmodo)
Foggy Canyon
Timelapse photography reveals the tide-like motions of fog that filled the Grand Canyon last week. This unusual meteorological condition was created by a temperature inversion. Usually air near the ground is warmest and the atmosphere cools as the altitude increases. But occasionally a mass of warm air will trap a layer of cooler air beneath it. In the case of the Grand Canyon, cool foggy air was capped by a warmer air mass, resulting in a sea of fog. Depending on the conditions, temperature inversions can create other distinctive weather patterns like cloud streets or even supercell thunderstorms. (Video credit: Vox; via Flow Visualization)
Cloud Streets
Cloud streets–long rows of counter-rotating air parallel to the ground in the planetary boundary layer–are thought to form as a result of cold air blowing over warm waters while caught beneath a warmer layer of air, a temperature inversion. As moisture evaporates from the warmer water, it creates thermal updrafts that rise through the atmosphere until they hit the temperature inversion. With nowhere to go, the warmer air tends to lose its heat to the surroundings and sink back down, creating a roll-like convective cell. (Photo credits: NASA Terra, NASA Aqua, and Tatiana Gerus)
