 EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes
and phenomena which shape our planet and our lives. EPOD will collect and
archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


 Surface Hoar Formation

   January 05, 2021

    Surface Hoar Formation

   Photographer:  Glenn McCreery
   Summary Author:  Glenn McCreery

    Frost forms when  water vapor  condenses directly into ice.
   Large  frost crystals (larger than about one-quarter inch or 0.6 cm
   across) that form are often called  hoarfrost. The most common form
   of hoarfrost is  surface hoar, which can occur, for example, on the
   top of a snowbank that’s warmed during the day and cooled at night
   under a clear, calm sky. Meltwater that  evaporates from within the
   snow is later recrystallized onto the colder surface. On sunny days,
   surface hoar is particularly noticeable when it glitters in reflected
   sunlight.
   This photo was captured one morning several weeks ago while cross
   country skiing above Pine Creek Pass, Teton County, Idaho, at an
   elevation of approximately 7,000 ft (2,133 m). The previous day’s high
   temperature was approximately 34 degrees F (1 degree C), but overnight
   temperatures dropped to about 4 degrees F (-15.5 degrees C), nearly
   ideal for hoarfrost formation.
   Note that in mountainous areas, if surface hoar is covered by new snow,
   it can form a very weak layer that’s prone to sliding, resulting in
   avalanche warnings being posted. Photo taken on November 29, 2020.
   Photo Details: Olympus TG4 camera, 30mm (35mm equivalent); f:9.0; ISO
   100; 1/320 second exposure for top photo and 1/200 second exposure for
   bottom photo (Macro mode for bottom photo).
     * Pine Creek Pass, Idaho Coordinates:  43.5716, -111.2152

Related EPODs

    Surface Hoar Formation  Not all Snow Crystals are Perfectly
   Symmetrical  Archive - Blue Light From Deep Snow  Archive - Lago
   Grey Icebergs  Iceberg Lagoon  EPOD 20th - Rideau River Pancake
   Ice
    More...

Cryosphere Links

     *  Guide to Frost
     *  What is the Cryosphere?
     *  Bentley Snow Crystals
     *  Glaciers of the World
     *  Ice, Snow, and Glaciers: The Water Cycle
     *  The National Snow and Ice Data Center Google Earth Images
     *  Snow and Ice Crystals

-
   Earth Science Picture of the Day is a service of the  Universities
   Space Research Association.

https://epod.usra.edu
 
