Atmosphere And Weather

Comparing the different Types of Snow Storms

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In 1923, the American poet Robert Frost penned his famous poem, "The Dust of Snow." Consisting of only eight lines, Frost vividly speaks of snow as a gentle life-changing experience, "The way a crow/shook down on me/the dust of snow/from a hemlock tree/has given my heart/a change of mood/and saved some part/of a day I had rued." The presence of snow not only is appreciated by Robert Frost but seems to have a magical effect on most people, whether it is a dust of snow from light snow flurries or a devastating nor'easter blizzard.

The earliest field of mysticism believed that water was the symbol of knowledge. Cosmically, rain and snow reflected in different ways for humankind to receive divine energy, flowing from a high spiritual plane. Today, science has discovered that snowstorms tell a lot about the climate of earth—with snow still providing a wealth of information.

Northeastern snowstorms of the United States form when warm, moist air masses from the Gulf of Mexico begin to move north. The actual snowstorm begins to form when this warm air collides with cold air masses moving southward from the Arctic. Snowstorms in northwestern United States develop when warm, moist air moves in from the Pacific Ocean, pushing upward into the cool air of the mountains. Factors like moisture content, air mass temperature and the direction of the air movement come into play. This affects the type and severity of each snowstorm that develops.

How snowstorms affect local weather patterns

Advancing technology has developed various weather satellites, radar and weather balloons, and ground-based weather patterns that collect data throughout the year. During the winter, they look at snow and ice in snowstorms that typically last two to five days. They not only collect information about large areas of snowstorms but research for local weather forecasts on a daily basis. The data gathered provides information on how much snow is falling over certain regions, developing winter conditions, types of air masses and local weather conditions.

Comparing different types of snowstorms

Every year, there is an average of 105 snowstorms in the United States, with the average snowfall amounting to approximately two inches. However, there are areas in the West that often see seven inches of snow per day. In between are several different types of snowstorms that are made worse by ice storms, freezing rain and ice pellets.

In the temperate continental climates, winter storms may occur in late autumn and early spring. In the Northern Hemisphere, the most powerful winter storms develop in March and possibly in April. Overall, the type of winter storm produced is dependent on the vertical temperature profile of the atmosphere over a specific area. This is when a series of temperature measurements are taken in the atmosphere at various levels. Different profiles mean different types of snowstorms with various characteristics

* Blizzard—one of the most severe winter storm conditions, a blizzard has heavy falling snow, strong winds, and low temperatures. The only difference between a blizzard and a snowstorm is the wind strength and reduced visibility. Blizzards are snowstorms that have an excess of 35 mph and reduced visibility of 1,300 feet for prolonged periods for three hours or more.

* Ground blizzards—this is the same as a blizzard except it stirs up snow that has already fallen on the ground.

* Lake Effect snowstorm—this type of snowstorm occurs when cold winds mover across large areas of warmer lake waters. If the same cold winds move over salt-water bodies, it would be called ocean effect snow, bay effect snow, or sea effect snow. A very intense storm, it can average over 200 inches . An area that is affected by this type of snowstorm are called snowbells—such as the Great Lakes, Western New York, northwestern Pennsylvania, northeast Ohio, western Michigan, upper Michigan, northwestern and north-central Indiana and central Ontario.

* Nor'easter—this huge scale snowstorm is a low-pressure area whose center of rotation is off the eastern coast, affecting the East Coast of the United States and Atlantic Canada. Its precipitation pattern not only involves heavy snowstorms but mimics extra-tropical storms that can cause hurricane force winds, coastal flooding and coastal erosion.

* Overrunning—occurring ahead of a trough in the upper atmospheric levels. As the jet stream dips to the southern Northern Hemisphere, a low-pressure trough is created which allows a mass of cold polar air to enter the United States. This can cause winter precipitation for 12-24 hours in duration with winter patterns causing precipitation to glaze northern areas.

*Snow flurries—a lack of significant snow accumulation falling on the ground during a snowstorm, falling in a very short duration.

* Snow showers—originating from cumuliform clouds, this snowfall consist of light to moderate durations. It is characterized by frozen precipitation that appears as snow. Having a very sudden beginning and ending, it may or may not leave snow on the ground.

* Snow or "Arctic" squall—this is a severe snowstorm, accompanied by very sudden and strong winds. Also referred to as the Lake Effect snowstorm, a favorite area is the Great Lakes.

* Upsloping—a condition that occurs in areas such as the eastern Rockies and Denver, Colorado, or the Appalachian Mountains-with lots of wintry precipitation. Areas of low pressure to the south move to meet the incoming east to northeast winds blowing in from the eastern Colorado plains. This forces air to rise upward—referred to as the upslope flow. Snow, sleet and freezing rain will not fall unless a cold polar air is present.

The following are various characteristics of winter storms, seen in advance of snowstorms or simply describing with makes them  unique to a specific winter storm.Different types of snowstorms are made of many different things, influenced by many things.

* Black ice—also called clear ice or glare ice, this is a very thin coating of glazed ice on a surface. Misnamed black ice, it is transparent which allows the black asphalt of the highway to shine through invisibly to drivers.

* Freezing rain—this type of winter weather causes very dangerous weather conditions for travelers along with major power outages. It consists of rain droplets that fall into shallow layers of cold air near the earth's surface, causing the droplets to freeze upon contact in the form of an ice glaze.

* Graupel—known as snow pellets, soft or small hail…this type of white and round/conical ice crystal falls through a cloud of super-cooled droplets below freezing temperature, but has not yet frozen. It will bounce when hitting the ground. Another way to phrase it is when a snowflake melts only halfway, then refreezes as it falls to the ground.

* Heavy showers with freezing rain—considered one of the most dangerous types of winter storms. This type of storm consists of sleet or freezing rain alternating between rain and snow. It is also called a "wintry mix," ranging from 28-36 °F.

* Rime—this is winter ice that is extremely hazardous to airliners, forming on the wings as the plane travels through clouds of super-cooled fog or cloud droplets. A milky white accumulation, riming is when super-cooled droplets attach to ice crystals in the form of graupel.

* Sleet—considered frozen precipitation that falls as ice pellets. It develops when snowflakes melt into raindrops as they pass through areas of warm air. The raindrops refreeze when falling into shallow layers of subfreezing air when they make contact with the ground.

* Snow—a major form of frozen precipitation that occurs during the winter, snow is a white or translucent six-sided hexagonal ice crystal. It requires temperatures to be below freezing in the atmosphere from the surface to cumuliform cloud levels. A "wet snow" forms when snow falls in above freezing temperatures in shallow layers.

* Snow creep—this involves the continuous and very slow, downhill movement of a snow layer.

* Snow depth—this is the actual depth of snow on the ground during a snowstorm, after a single snowstorm or series of snowstorms.

* Snowfall—this involves the rate at how fast snow falls, expressed in inches of snow depth every six hours.

* Snow banner—resembling smoke coming from a volcano, the snow banner is a plume of snow blowing off the top of a mountain.

* Whiteouts—reduced visibility and contrast from excessive amounts of falling snow in specific areas. People who live in densely populated areas take major chances of road accidents or while flying in this type of winter weather. There are four different types of whiteouts: in blizzards, lake effect or mountain effect snow, optical illusions of polar regions (also called flat light or sector whiteout), or with ground-level thick fog

* Wind chills—a temperature calculation that takes into consideration the human body temperature and wind effects. It describes what the average loss of body heat is on a person and how the outside temperature feels to them. It does not consist of the actual air temperatures. The Central Plains in the United States, running from the Gulf of Mexico into Canada, has severe blizzard conditions that have wind chills of -40 °F or more plus whiteout conditions.

More about this author: Nancy Houser

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