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Spring has Sprung! Hey, Wait a Second...

By By Gina Cherundolo, AccuWeather.com Staff Writer
March 16, 2011, 4:33:11 AM EDT

If you thought the first full day of spring was March 21, you might be surprised to know that there are at least three different classifications of the spring season, one of which began Tuesday.

March 1 marks the first day of meteorological, or climatological, spring for the Northern Hemisphere.

The vernal equinox occurs the evening of March 20 in the United States. This event, when the Earth's tilt on its axis is neither toward nor away from the sun, marks the start of astronomical spring. Likewise, this event repeats in September for the autumnal equinox.


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Unlike astronomical seasons, which are determined by the Earth's position in relation to the sun, meteorological seasons are categorized by temperature.

Meteorological winter is the coldest quarter of the year (December-February), while meteorological summer is the warmest (June-August). The quarter between these periods is meteorological spring, with occurs from March through May.


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Additionally, there are solar seasons, which are categorized by the length of daylight hours. Solar winter is November-January, the months with the shortest daylight hours. Because of this, solar spring began in February.

No matter what way you want to think of the seasons, the start of March will inevitably lead to warmer temperatures and the end of the winter weather.

Additionally, Paul Pastelok, leader of the AccuWeather.com Long-Range Forecasting Team, has released his Spring 2011 Forecast for the United States, and AccuWeather.com Expert Senior Meteorologist Brett Anderston has released his Spring 2011 Forecast for Canada.

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