FYFD

Tag: cloud formation

  • Seeding Clouds

    Seeding Clouds

    In the remote South Atlantic, north of the Antarctic Circle, sit the volcanic Zavodovski and Visokoi islands. Though only roughly 500 and 1000 meters tall, respectively, each island disrupts the atmosphere nearby, often generating cloudy wakes. In today’s pair of images, the northerly Zavodovski has a particularly bright cloud wake, thanks to sulfate aerosols degassing from its volcano, Mount Curry. Though it’s hard to pick out the effect in the natural-color image above, the false-color version below shows the bright wake clearly. The filtering on this image turns snow and ice — like that on Visokoi’s peak — red and makes the water vapor of clouds white. The sulfates from Mount Curry act as nucleii for water droplets, forming many small, reflective drops that stand out against the rest of the sky. (Image credit: W. Liang; via NASA Earth Observatory)

    This false-color satellite image highlights the volcanic seeding by filtering snow and ice as red and water vapor in clouds as white.
    This false-color satellite image highlights the volcanic seeding by filtering snow and ice as red and water vapor in clouds as white.
  • Rolling Over Wisconsin

    Rolling Over Wisconsin

    Although they may look sinister, roll clouds like this one are no tornado. These unusual clouds form near advancing cold fronts when downdrafts cause warm, moist air to rise, cool below the dew point, and condense into a cloud. Air in the cloud can circulate around its long horizontal axis, but the clouds won’t transform into a tornado. Roll clouds are also known as Morning Glory clouds because they often form early in the day along the Queensland coast, where springtime breezes off the water promote their growth. The clouds do form elsewhere, though; this example is from Wisconsin in 2007. (Image credit: M. Hanrahan; via APOD)

  • Clouds Down Under

    Clouds Down Under

    This large and unusual cloud formation was captured one July morning over western Australia. Stretching over 1,000 kilometers, the clouds have interesting features at both the large and small scale. The small-scale ripples within the clouds are gravity waves triggered by the terrain below. The larger, arced features are tougher to explain, though they may also be related to gravity waves and terrain, just on a much larger scale. They also resemble fallstreak clouds where supercooled droplets evaporate from the inside of the cloud out. (Image credit: W. Liang; via NASA Earth Observatory)

  • Wave Clouds From Space

    Wave Clouds From Space

    An astronaut snapped this image of wave clouds formed around the Crozet Islands, which lie between South Africa and Antarctica. Clouds like these form when warm, moist air gets pushed up and over a mountain. As it rises, the air cools and its pressure decreases, causing condensation. Pushed out of equilibrium, gravity then pulls the air back downward in the wake of the mountain. That warms the air, causing evaporation. Like a mass bouncing on a spring, the air continues to yo-yo up and down, forming cloudy stripes and clear ones until the energy from its mountain climb is spent. (Image credit: NASA; via NASA Earth Observatory)

  • Featured Video Play Icon

    “Níłtsą́”

    Living in the central and western United States, it’s easy to dismiss summer weather as just another storm, but the truth is that this region sees some of the most majestic and spectacular thunderstorms in the world. And no one captures that grandeur better than storm-chasing photographer Mike Olbinski. His latest film is named for the Navajo word for rain and features over 12 minutes of the best storms from 2021 and 2022. Towering turbulent clouds grow by convection, lightning splits the night sky, and microbursts pour down from above. As always, it’s a stunning depiction of the power of atmospheric fluid dynamics. (Image and video credit: M. Olbinski)

  • Ominous Mammatus

    Ominous Mammatus

    Mammatus clouds are fairly unusual and often look quite dramatic. Most clouds have flat bottoms, caused by the specific height and temperature at which their droplets condense. But mammatus clouds have bubble-like bottoms that are thought to form when large droplets of water or ice sink as they evaporate. Although they can occur in the turbulence caused by a thunderstorm, mammatus clouds themselves are not a storm cloud. They appear in non-stormy skies, too. The clouds are particularly striking when they’re lit from the side, as in the image above. (Image credit: J. Olson; via APOD)

  • Cellular Clouds

    Cellular Clouds

    Though tough to make out from the surface, our oceans are often covered by cell-shaped clouds stretching thousands of kilometers. This satellite image shows off two such types of marine stratocumulus cloud. Open-celled clouds appear as thin wisps of vapor around an empty middle; in these clouds, cool air sinks through the center while warm air rises along the edges. Open-celled clouds are good rain producers.

    On the flip side, closed-cell clouds have a vapor-filled center and breaks in the cloud cover along each cell’s edge. These clouds don’t produce much rain, but they do lift warm, moist air through their middles and let cool air sink along their edges. Closed-cell clouds tend to last much longer than their open-celled counterparts; they can stick around for half a day, whereas open-celled clouds break up in only a couple hours. (Image credit: J. Stevens; via NASA Earth Observatory)

  • Cloud Streets

    Cloud Streets

    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)

  • Inhibiting Marine Lightning

    Inhibiting Marine Lightning

    Thunderstorms over the ocean have substantially less lightning than a similar storm over land. Scientists wondered whether this difference could be due to lower cloud bases over the ocean or differences in the cloud droplets’ nuclei. But a new study instead implicates coarse sea spray as the deciding factor. By tracking the full lifetime of storm systems through remote sensing, the team found that fine aerosols can increase lightning activity over both land and ocean. But adding coarse sea salt from sea spray reduced lightning by 90% regardless of fine aerosols. With sea salt in the mix, clouds seem to develop fewer but larger condensation droplets, providing less opportunity for the electrification necessary to generate lightning. (Image credit: Z. Tasi; research credit: Z. Pan et al.)

  • Actinoform Clouds

    Actinoform Clouds

    Flower-shaped actinoform clouds, like those seen on the left side of this satellite image, were only discovered in the 1960s once satellite imagery allowed meteorologists to identify cloud structures that were too large to recognize from the ground. Often appearing over the ocean, these clouds can stretch over hundreds of kilometers, bringing drizzling rain.

    This particular set of actinoform clouds have some distinctive neighbors in the right side of the image, where V-shaped slashes through the cloud cover mark the origins of two von Karman vortex streets. The vortex streets appear downwind of two rocky islands, Alejandro Selkirk Island and Robinson Crusoe Island. (Image credit: L. Dauphin; via NASA Earth Observatory)