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Pursuit of Passion

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fog rimeI bestirred myself at the light of dawn to an ethereally splendid frost and fog swaddling the city in entirety. Days like these upraise my spirit to persevere the unusually lengthy season of monochromatic algidity.

Contemplating the benevolence and malevolence of eons of wintertides , I resorted to proclaim and accentuate its heterogeneity.

Seasonal snow is an important factor in Earth’s climatic system as it not only aids in regulating the Earth’s surface temperature but the melting snow, helps fill rivers and reservoirs across the United States. Did you know that, snow cover is the largest single component of cryosphere, covering an average of about 46 million square kilometers (about 17.8 million square miles) of Earth’s surface every year. About 98 % of the Earth’s snow cover is located in the Northern Hemisphere. On such a large scale, snow cover helps regulate the exchange of heat between Earth’s surface and atmosphere, or the Earth’s energy balance. On a smaller scale, variations in snow cover can affect regional weather patterns.

Snow formation requires two specific weather conditions: low temperatures and sufficient moisture in the atmosphere. In warm, humid places, such as Florida, there is significant moisture in the air, but temperatures are rarely low enough to produce snow. And while many deserts get quite cold in the winter, there is often not enough moisture in the atmosphere to produce snow. Even Antarctica, the coldest and iciest continent, contains a region called the Dry Valleys, where it is extremely cold, but so dry that snow seldom occurs.

Snow is most common in high altitudes and latitudes, particularly among the mountainous regions of the Northern Hemispheres. Snow falls in the Southern Hemisphere during the austral winter, primarily in Antarctica, the high mountains of New Zealand and South America.

Snow is associated with other geographical features like large lakes, called Lake Effect Snow. Cold, dry air hovering over lakes, exchange moisture and heat from its relatively warm waters. The heated air rises, cools off, condensing moisture in clouds producing snow once they reach  land. Lake effect snow is common along the southern and eastern edges of the Great Lakes in the United States and near the Great Salt Lake in Utah, as well as around some of the large lakes in Canada and Europe. The United Kingdom, Japan, and Korea also experience similar phenomena, but the snow-producing moisture comes from the surrounding oceans instead of lakes.

Nor’easters can occur in the eastern United States any time between October and April, when moisture and cold air are plentiful. A Nor’easter is named for the winds that blow in from the northeast and drive the storm up the east coast along the Gulf Stream, a band of warm water that lies off the Atlantic coast. They are known for dumping heavy amounts of rain and snow, producing hurricane-force winds, and creating high surfs that cause severe beach erosion and coastal flooding.

The wind chill is the temperature your body feels when the air temperature is combined with the wind speed. The higher the wind speed the faster exposed areas of your body lose heat and the colder you feel.

Frostbite is damage to the skin due to prolonged exposure to cold temperatures, usually below 32° F.

Snow cover is a part of the cryosphere, tracing its origin to the Greek word kryos for frost. Snow is other term is precipitation of ice crystals, originating in clouds when temperatures are below the freezing point (0 degrees Celsius, or 32 degrees Fahrenheit), condensing water vapor directly into ice crystal skipping the liquid stage. Once an ice crystal has formed, it absorbs and freezes additional water vapor from the surrounding air, growing into a snow crystal or snow pellet, which then free falls to Earth.

Atmospheric conditions affect how snow crystals form and what happens to them as they fall from clouds to the ground.

Snow crystals

Snow may fall as symmetrical, six-sided made of as many as 200 ice crystals or snowflakes, everyone associates a snowflake with or it may fall as larger clusters of clumped snowflakes or polycrystalline or papery flakes called flurries or loose powdery snow. Snowflakes form in clouds where the temperature is below freezing. The ice crystals form around tiny bits of dirt that has been carried up into the atmosphere by the wind. As the snow crystals grow, they become heavier and fall toward the ground.

Bright snow blinds us with its gleaming white color because it reflects beams of white light. Instead of absorbing light, snow’s complex structure prevents the light from shining through its lattice formation. A beam of white sunlight entering a snow bank is so quickly scattered by a zillion ice crystals and air pockets that most of the light comes bouncing right back out of the snow bank. What little sunlight is absorbed by snow is absorbed equally over the wavelengths of visible light thus giving snow its white appearance. So while many natural objects get their blue, red, and yellow colors from absorbing light, snow is stuck with its white color because it reflects light.

 

Sleet, or ice pellets, are small, translucent balls of ice. Sleet is often the result of rain that freezes as it falls to the ground. Sleet is composed of drops of rain or drizzle that freeze into ice as they fall, and is sometimes called a wintery mix of rain and snow. These small, translucent balls of ice are usually smaller than 0.30 inches in diameter. Official weather observations may list sleet as ice pellets. In some parts of the United States, the term sleet can refer to a mixture of ice pellets and freezing rain.

Graupel are rounded, opaque ice or snow pellets ranging from 0.1 to 0.2 inches in diameter. They form as ice crystals fall through supercooled cloud droplets, which are below freezing but remain a liquid. The cloud droplets then freeze to the crystals, forming a lumpy mass. Graupel is sometimes mistaken for hail, but tends to have a texture that is softer and more crumbly. Hail is always associated with severe thunderstorms of spring and summer not winter with a harder texture that holds up longer.

Dew is to frost as raindrops are to snowflakes. Water vapor condensing into liquid is the antecedent for raindrops and dew and on condensing into ice procreates snowflakes and frost like Hoarfrost and Rime.

Hoar frost

Hoar Frost is composed of larger interlocking, delicately feathery and flaccid ice crystals that evenly engulfs exposed substratum reverberating light from its crystals and appearing white in general and transparent when reflecting sun.

Rime is freezing fog forming on a frigid, foggy and windy overnight conditions. Super-cooled fog water droplets impinge upon gelid objects  instantaneously freezing entire droplet.

As multiple cold fog droplets strike the windward side of any exposed object builds up a mass of porous, opaque crystals loaded with air spaces. The rime grows horizontally into milky white stars, needles and feathers.

 

 

Rime

Whereas rime usually builds up moderately in lowland areas it may accumulate to an ice cover of several feet in mountaineous regions. In fact rime ice makes up a significant source for valley glaciers as it breaks away falling into the valley below.

 

Rime usually accumulates best on exposed obstacles, such as trees, radio masts or rock pinnacles. It might sometimes cause some structural damage, but generally far less severe than black ice or glaze.

 

 

Black ice or Glazed frostGlaze frost is a coating of ice, generally clear and smooth. It occurs when supercooled water droplets deposited by rain, drizzle, fog, or condensed water vapor strike an exposed object at temperatures at or below freezing. Factors favoring formation of glaze or black ice or clear ice are large drop size, rapid accretion, slight supercooling, and slow dissipation of the latent heat of fusion. Glaze is denser, harder, and more transparent than rime and looks similar to an ice cube.

 

A blizzard is a violent winter storm, lasting at least three hours, which combines subfreezing temperatures and very strong wind laden with blowing snow that reduces visibility to less than 0.25 miles. Blizzard is a long-lasting snowstorm with very strong winds and intense snowfall. You need three things to have a blizzard; cold air at the surface, lots of moisture, and lift. Warm air must rise over cold air. A snowstorm features large copious amounts of snowfall.

A snow flurry is snow that falls for short durations and with varying intensity; flurries usually produce little accumulation especially with blowing winds.

A snow squall is a brief, but intense snowfall that greatly reduces visibility and which is often accompanied by strong winds.

A snowburst is a very intense shower of snow, often of short duration, that greatly restricts visibility and produces periods of rapid snow accumulation.

Drifting and blowing snow are the result of snow particles being raised from the ground by the wind. To classify wind-driven snow as drifting snow, the particles will only be lifted to shallow heights (less than 6 feet) and the horizontal visibility will remain more at eye level (6 feet). When the wind drives snow to levels 6 feet or higher and the visibility is restricted to 6 miles or less, it is classified as blowing snow.

Drifting snow

 

Snow cover, also called snowpack, is the total of all the snow and ice on the ground. It includes both new snow and previous snow and ice that have not melted.

New snow is a recent snow deposit in which the original form of the ice crystals can be recognized.

Firn is rounded, well-bonded snow that is older than a year or perennial snow and has a density greater than 55 % and thankfully ours melt away as its seasonal snow before firming to a firn.

Névé is young, granular snow that has been partially melted, refrozen and compacted; névé that survives a full melt season is called firn. This type of snow is associated with glacier formation.

 

Sundogs, parhelia, are formed by plate crystals high in the cirrus clouds that occur world-wide. In cold climates the plates can also be in ground level as diamond dust.

 

The plates drift and float gently downwards with their large hexagonal faces almost horizontal. Rays that eventually contribute their glint to a sundog enter a side face and leave through another inclined 60° to the first. The two refractions deviate the ray by 22° or more depending on the ray’s initial angle of incidence when it enters the crystal. The condition where the internal ray crossing the crystal is parallel to an adjacent face gives the minimum deviation of about 22°.

 

Red light is refracted less strongly than blue and the inner, sunward, edges of sundogs are therefore red hued.

 

Rays passing through plates crystals in other ways form a variety of halos.

 

When the sun is relatively high, rays cannot pass through the crystal unless they are channeled by being internally reflected from the upper and lower basal (large hexagonal) faces. The skewed angle of incidence also causes the ray deviation to increase and high sun sundogs are farther from the sun.

 

Plate crystals rarely float exactly horizontal, they wobble and the wobble increases with crystal size. Wobbly plates produce tall sundogs and in the more extreme cases the distinction between a tall sundog and fragments of a 22° halo becomes somewhat arbitary.

 

The moon forms halos just like the sun. Its equivalent of sundogs are called paraselenae or parselenae. Lunar halos are intrinsiclly faint and to see them dark surroundings and a near full moon are best. Visually they often appear colourless or almost so because their light is not strong enough to excite the color sensors in our eyes.

Here are few of my fave quotes.

“Spring passes and one remembers one’s innocence.

Summer passes and one remembers one’s exuberance.

Autumn passes and one remembers one’s reverence.

Winter passes and one remembers one’s perseverance.”

–Yoko Ono

“I wonder if the snow loves the trees and fields, that it kisses them so gently? And then it covers them up snug, you know, with a white quilt; and perhaps it says “Go to sleep, darlings, till the summer comes again.”

― Lewis Carroll, Alice’s Adventures in Wonderland & Through the Looking-Glass― Yoko Ono