Living in southern Arizona makes one appreciate clouds since we don’t get to see them very often. We average almost 200 sunny days and about 100 partly sunny days a year and, when we are lucky enough to have clouds – esp. late in the day – we get some absolutely gorgeous sunsets.
Clouds are an intricate part of our existance on our little planet and most people probably don’t pay too much attention to them, but sometimes the right conditions can create some incredible formations and visuals.
We hope you enjoy today’s Friday Fotos and some explanations about each … and keep your eyes on the skies since nature can provide some spectacular views.
Accuweather explains shelf clouds often form at the leading edge of a gust front or outflow boundary from a thunderstorm, or strong winds flowing down and outward from a storm. The outer part of a shelf cloud is often smoother with a notable rising motion exhibited by a tiered look (hence, the name shelf cloud). Underneath, a turbulent, unsettled appearance is often the case. A shelf cloud should be seen as a harbinger of strong winds, so take caution.
NASA Explanation: What kind of clouds are these? Although their cause is presently unknown, such unusual atmospheric structures, as menacing as they might seem, do not appear to be harbingers of meteorological doom. Known informally as Undulatus asperatus clouds, they can be stunning in appearance, unusual in occurrence, are relatively unstudied, and have even been suggested as a new type of cloud. Whereas most low cloud decks are flat bottomed, asperatus clouds appear to have significant vertical structure underneath. Speculation therefore holds that asperatus clouds might be related to lenticular clouds that form near mountains, or mammatus clouds associated with thunderstorms, or perhaps a foehn wind — a type of dry downward wind that flows off mountains. Such a wind called the Canterbury arch streams toward the east coast of New Zealand’s South Island. The above image, taken above Hanmer Springs in Canterbury, New Zealand, in 2005, shows great detail partly because sunlight illuminates the undulating clouds from the side.
Lenticular Clouds Over Washington
Credit & Copyright: Tim Thompson via NASA
NASA Explanation: Are those UFOs near that mountain? No — they are multilayered lenticular clouds. Moist air forced to flow upward around mountain tops can create lenticular clouds. Water droplets condense from moist air cooled below the dew point, and clouds are opaque groups of water droplets. Waves in the air that would normally be seen horizontally can then be seen vertically, by the different levels where clouds form.
NASA Explanation: Pictured, behind this darker cloud, is a pileus iridescent cloud, a group of water droplets that have a uniformly similar size and so together diffract different colors of sunlight by different amounts. The above image was taken just after the picturesque sight was noticed by chance by a photographer in Ethiopia. A more detailed picture of the same cloud shows not only many colors, but unusual dark and wavy bands whose origins are thought related to wave disturbances in the cloud.
NASA explanation: Is that a spaceship or a cloud? Although it may seem like an alien mothership, it’s actually a impressive thunderstorm cloud called a supercell (sometimes called a mothership cloud). Such colossal storm systems center on mesocyclones — rotating updrafts that can span several kilometers and deliver torrential rain and high winds including tornadoes. Jagged sculptured clouds adorn the supercell’s edge, while wind swept dust and rain dominate the center.
Morning Glory Clouds Over Australia
Credit & Licence: Mick Petroff via NASA
NASA Explanation: What causes these long, strange clouds? No one is sure. A rare type of cloud known as a Morning Glory cloud can stretch 1,000 kilometers (621 miles) long and occur at altitudes up to two kilometers (1.2 miles) high. Although similar roll clouds have been seen at specific places across the world, the ones over Burketown, Queensland Australia occur predictably every spring. Long, horizontal, circulating tubes of air might form when flowing, moist, cooling air encounters an inversion layer, an atmospheric layer where air temperature atypically increases with height. These tubes and surrounding air could cause dangerous turbulence for airplanes when clear. Morning Glory clouds can reportedly achieve an airspeed of 60 kilometers per hour (37 mph) over a surface with little discernible wind.
A Sonic Boom
Credit: Ensign John Gay, USS Constellation, US Navy via NASA
NASA Explanation: When an airplane travels at a speed faster than sound, density waves of sound emitted by the plane cannot precede the plane, and so accumulate in a cone behind the plane. When this shock wave passes, a listener hears all at once the sound emitted over a longer period: a sonic boom. As a plane accelerates to just break the sound barrier, however, an unusual cloud might form. The origin of this cloud is still debated. A leading theory is that a drop in air pressure at the plane described by the Prandtl-Glauert Singularity occurs so that moist air condenses there to form water droplets. Above, an F/A-18 Hornet was photographed just as it broke the sound barrier.
Stay safe and have a great weekend! 🙂 j & B