Icaria, Greece
June 15, 2011
Image Credit & Copyright: Chris Kotsiopoulos
Kamis, 28 Februari 2013
Rabu, 27 Februari 2013
Asperatus Clouds over New Zealand
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. This image, taken above Hanmer Springs in Canterbury, New Zealand, in 2005, shows great detail partly because sunlight illuminates the undulating clouds from the side.
Image Credit & Copyright: Witta Priester
Explanation: http://apod.nasa.gov/apod/ap130227.html
Supercell
A supercell is a thunderstorm that is characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. For this reason, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms (supercell, squall line, multi-cell, and single-cell), supercells are the overall least common and have the potential to be the most severe. Supercells are often isolated from other thunderstorms, and can dominate the local climate up to 32 kilometres (20 mi) away.
Senin, 25 Februari 2013
Alaskan Moondogs
Moonlight illuminates a snowy scene in this night land and skyscape made on January 17, 2013 from Lower Miller Creek, Alaska, USA. Overexposed near the mountainous western horizon is the first quarter Moon itself, surrounded by an icy halo and flanked left and right by moondogs. Sometimes called mock moons, a more scientific name for the luminous apparitions is paraselenae (plural). Analogous to a sundog or parhelion, a paraselene is produced by moonlight refracted through thin, hexagonal, plate-shaped ice crystals in high cirrus clouds. As determined by the crystal geometry, paraselenae are seen at an angle of 22 degrees or more from the Moon. Compared to the bright lunar disk, paraselenae are faint and easier to spot when the Moon is low.
Image Credit & Copyright: Sebastian Saarloos
Explanation: http://apod.nasa.gov/apod/ap130126.html
Minggu, 24 Februari 2013
A Lenticular Cloud over New Zealand
What's happening above those mountains? Several clouds are stacked up into one striking lenticular cloud. Normally, air moves much more horizontally than it does vertically. Sometimes, however, such as when wind comes off of a mountain or a hill, relatively strong vertical oscillations take place as the air stabilizes. The dry air at the top of an oscillation may be quite stratified in moisture content, and hence forms clouds at each layer where the air saturates with moisture. The result can be a lenticular cloud with a strongly layered appearance. This picture was taken in 2002 looking southwest over the Tararua Range mountains from North Island, New Zealand.
Image Credit & Copyright: Chris Picking
Explanation from: http://apod.nasa.gov/apod/ap090121.html
Sabtu, 23 Februari 2013
Sunrise Solstice at Stonehenge
This picture was taken during the week of the 2008 summer solstice at Stonehenge in United Kingdom, and captures a picturesque sunrise involving fog, trees, clouds, stones placed about 4,500 years ago, and a 5 billion year old large glowing orb. Even given the precession of the Earth's rotational axis over the millennia, the Sun continues to rise over Stonehenge in an astronomically significant way.
Image Credit & Copyright: Max Alexander, STFC, SPL
Explanation from: http://apod.nasa.gov/apod/ap100621.html
Kamis, 21 Februari 2013
NASA's SDO Observes Fast-Growing Sunspot
As magnetic fields on the sun rearrange and realign, dark spots known as sunspots can appear on its surface. Over the course of Feb. 19-20, 2013, scientists watched a giant sunspot form in under 48 hours. It has grown to over six Earth diameters across but its full extent is hard to judge since the spot lies on a sphere not a flat disk.
The spot quickly evolved into what's called a delta region, in which the lighter areas around the sunspot, the penumbra, exhibit magnetic fields that point in the opposite direction of those fields in the center, dark area. This is a fairly unstable configuration that scientists know can lead to eruptions of radiation on the sun called solar flares.
Image Credit: NASA/SDO/AIA/HMI/Goddard Space Flight Center
Explanation from: http://www.nasa.gov/mission_pages/sdo/news/fastgrowing-sunspot.html
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