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°hoarfrost of last January°°


°hoarfrost of last January°°
Photo Information
Copyright: Sergio Stella (flashpoint) Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 630 W: 133 N: 4324] (28008)
Genre: Plants
Medium: Color
Date Taken: 2009-01-10
Categories: Trees
Camera: Nikon D40X, AF-S MICRO-NIKKOR 105mm f/2.8G ED
Exposure: f/8, 1/125 seconds
More Photo Info: [view]
Photo Version: Original Version, Workshop
Date Submitted: 2010-12-20 11:07
Viewed: 2392
Points: 10
[Note Guidelines] Photographer's Note

foto dello scorso Gennaio,che si affianca a quella pubblicata dall'amico Roberto,per mostrare il caratteristico deposito di ghiaccio a forma di aghi e scaglie della galaverna sui rami di Robinia pseudoacacia.....

Radiation frost (also called hoar frost or hoarfrost or pruina ) refers to the white ice crystals, loosely deposited on the ground or exposed objects, that form on cold clear nights when heat losses into the open skies cause objects to become colder than the surrounding air. A related effect is flood frost which occurs when air cooled by ground-level radiation losses travels downhill to form pockets of very cold air in depressions, valleys, and hollows. Hoar frost can form in these areas even when the air temperature a few feet above ground is well above freezing. Nonetheless the frost itself will be at or below the freezing temperature of water.

Hoar frost may have different names depending on where it forms. For example, air hoar is a deposit of hoar frost on objects above the surface, such as tree branches, plant stems, wires; surface hoar is formed by fernlike ice crystals directly deposited on snow, ice or already frozen surfaces; crevasse hoar consists in crystals that form in glacial crevasses where water vapour can accumulate under calm weather conditions; depth hoar refers to cup shaped, faceted crystals formed within dry snow, beneath the surface.

Surface hoar is a cause of avalanches when it forms on top of snow. Conditions that are ideal are cold clear nights, with a very light wind that is able to circulate more humidified air around the snow surface. Wind that is too abrupt will destroy the crystals. When buried by subsequent snows they may remain standing for easy identification, or become laid down, but still dangerous because of the weakness of the crystals. In low temperatures surface hoar can also be broken apart and blown across the surface forming yukimarimo.

Hoar frost also occurs around man-made environments such as freezers or industrial cold storage facilities. It occurs in adjacent rooms that are not well insulated against the cold or around entry locations where humidity and moisture will enter and freeze instantly depending on the freezer temperature.

surce Wikipedia


my mood today is No Better Than This-John Mellencamp

Make: NIKON CORPORATION
Model: NIKON D40X
Software: Adobe Photoshop CS4 Windows
Exposure Time: 8/1000 sec
F-Stop: f/8.0
ISO Speed Ratings: 100
Focal Length: 105/1 mm
Date Taken: 2009-01-10 09:54
Metering Mode: Pattern
File Size: 224 kb

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To Hormon_Manyer: no problem for green smilies.....flashpoint 1 12-20 14:57
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Critiques [Translate]

Incredible DOF and sharpness. Amazing composition. And thanks for adding the explanation about hoarfrost. TFS!

Ciao Sergio. Grazie per la citazione. Una luce delicatissima accompagna questa galaverna che a livello di spettacolo e sempre una sicurezza.

Roberto

Ciao Sergio,

Your previous image was a stunner, but this one, by my opinion, isn't. Only a very small part is sharp enough, even the closer parts of the branch are out of focus. I prefer the workshop photo which has better sharpness and the composition's more interesting, too.

Have a great festive season, friendly regards, Ladislao

(Sorry, out of smileys for today. Didn't realize.)

  • Great 
  • lousat Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 6595 W: 89 N: 15659] (65489)
  • [2010-12-20 14:38]

Molto bella Sergione,una macro con contorno soft e con tanto tanto freddo che ti sei preso,meriti un plauso anche per quello.Buona giornata,Luciano

  • Great 
  • joska Gold Star Critiquer/Gold Note Writer [C: 806 W: 0 N: 4092] (22535)
  • [2010-12-21 0:24]

Hi Sergio,
Splendid winter photo, TFS!

Ciao Sergio, bella galaverna ripresa in maniera ottimale. perfetta la gestione del bianco. Un saluto ed un buon Natale, Paolo

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