Rime-Purple

 RIME BEN B. AND LILLY B. Purple Class

Introduction Rime is a white, milky granular deposit of ice, that forms when super-cooled water in fog or low level clouds, comes into contact with an object (1,2,5). When this happens, the water instantly freezes into ice. The fog or clouds, when persisted over long periods of time, can build Rime up to dangerous levels (2). Rime can accumulate to several feet in mountainous regions and a few inches in lower altitude regions (5,6). media type="youtube" key="qXH8sEws3BI" height="261" width="470" align="right"



Dangers Rime forms on exterior objects, and can cause damage in extreme circumstances. Rime can build up to dangerous levels when the fog or low lying clouds persist over long periods of time (2). Rime build up can grow to several inches, and can cause the objects it is attached to, to break due to the added weight on a easily breakable, frozen object (2). The most common instances of Rime forming are on radio towers, power lines, trees, and mainly any exposed object to the wind (8,9). The most danger can arise when the Rime breaks a power line (9). This may cause power outages to many areas, as well as exposing a live wire on the road (9). If not treated quickly, many problems can evolve from this as cars will swerve to avoid it, and skid on the frozen road, or possibly electrocute someone who comes into contact with the water it is touching, as water is a very good conductor of electricity. More problems can occur from Rime because it may cover the steps or walkways endangering commuters, possibly causing them to fall and injure themselves. Rime can also form on the outside of airplanes, which causes them damage and can result in a plane crash by overwhelming their de-icing protection system, and effecting the controlling of the aircraft, increasing drag and decreasing lift. (7).



Conditions of Formation In order for RIme to form, certain conditions must be present. The temperature of the air mass must be below freezing, the water at super-cooled temperatures, as well as the object that the air is coming into contact with to create Rime (1). The air mass being saturated, specific humidity equaling the capacity of the air, the capacity is lower because the air is colder, with liquid drops present because of condensation is another necessary condition for Rime to form (1,2). Because of the small size of the droplets of water, the heat is released from them quickly, allowing the ice to form on a specific area, preventing it from spreading (3). The more fog that is present on the windward side of the object the Rime is forming on, the more Rime is able to form. When rime forms, it creates interlocking ice crystals, allowing for air to be trapped in between them (2,3). This trapped air gives Rime its' opaque/white color (3). Foggy conditions in sub-freezing temperatures are prime conditions for Rime to form (2). In the 1st picture, the wind is blowing from behind the person, because Rime forms into the wind.

Historical Examples In December of 1994, a severe storm deposited around a centimeter of Rime Ice on a 425 foot, self supporting tower in Martinsville, Virginia. This tower was built in 1950 and was 44 years old. Three out of the four support bases were damaged due to the Rime. They were cracked and needed repair to prevent any more damage to the tower, and the surrounding area if the tower fell over. The bases were repaired, and shipped to a local business for a damage assessment. What they found was that along with the big cracks, there were also hairline cracks (very small ones), which can go unseen and cause damage. (8 for all)

Safety Predicting whether Rime is going to form or not is fairly easy, and therefore it is easy to prepare Rime. Rime is a granular ice that forms on outdoor objects, such as trees, steps, and telephone/electrical wires. Rime can cause damage to these things by making the steps slippery which may cause someone to fall and hurt themselves, tree limbs to break, or power to go out. To ready your self for such conditions, such precautions may be taken. First, make sure salt or a de-iceing material is easily accesable. This will help to clear steps and walkways of dangerous rime reducing the risk of falling and resulting injury while walking on them. Tree limbs are harder to control, but proper landscape care and awareness of and branches hanging over your house can prevent any possible damage from falling limbs. To prepare for power outages, one should have many readily available flash lights to help them see, and prevent in house injuries due to lack of sight. For airplanes, make sure that proper de-icing equipment is in use, and avoid flying for long distances in clouds because no aircraft is immune to icing and the resulting damage (7).



**LINKS**: This website really captures the beauty of rime ice within it's pictures. It also gives a basic background of what rime ice is. Click here to find out! For more information about aircraft dangers, what dangers they cause and how to avoid them, click here

Sources (1) "Rime January 2001." //NOAA//. NOAA. Web. 11 Jan. 2012. . (2) "Rime Ice - Piqua, Ohio." //NOAA//. NOAA. Web. 11 Jan. 2012. . (3) "Dew, Hoar Frost, Rime & Glaze." //Weatherfaqs.org.uk/node/173//. Weather FAQs. Web. 2012. . (4) "Olympic National Park: Rime Ice on Hurricane Ridge." //LeeRentz//. Lee Rentz Photography. Web. 2012. . (5) "Rime." //Weather Online//. Weather Online. Web. 2012. . (6) "Heavy Rime Icing Event." //NOAA.// NOAA. Web. 15 Jan. 2012. . (7) "What Is Flight Icing?" //NOAA//. NOAA NESDID STAR. Web. Jan 18 2012. . (8) "Check Towers After Ice and Snow." //Radio World//. Radio World. Web. 18 Jan 2012. . (9) "Rime across Northern Colombia Basin." NOAA. //NOAA.// Web. 21 Jan. 2012. <http://www.wrh.noaa.gov/otx/photo_gallery/rime_23Jan09.php>.