Spring has sprung...

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  • Flowering plants burst into colour in Cannon Hill Park, Birmingham. Credit: Joe Giddens/PA Wire.

    A depiction of how the Earth moves around the Sun, creating our seasons. Credit: NOAA.

    Forecast minimum air temperatures for this coming Sunday, showing a cold night for many areas.

  • Spring has sprung...
    20.03.2014 17:20

     

    Today, Thursday 20th March 2014, marks the beginning of Spring in an astronomical sense. This is what much of the public goes by when heralding the start of Spring, and is commonly marked on calendars (although from year to year the date itself wavers by a day). The astronomical definition of Spring is based on the passage of the Earth around the sun, with the four quarters of this elliptic orbit coinciding with our four seasons. The Summer months occur when the northern hemisphere of the Earth, tilted on its axis as it is, is inclined towards the sun, with the Summer Solstice marking the height of this period and giving us our longest day. Conversely, the Winter Solstice denotes the shortest day. Thus, our Spring Equinox (and the Autumn Equinox in roughly six months time), signifies the midway point between Winter and Summer, when day and night are almost equal in length.

    However, when it comes to meteorology, we often take a different view on the arrival of Spring. In our world, Spring sprang a couple of weeks ago, on 1st March. But why do we do things differently? As alluded to above, the astronomical definition leads to seasons falling on slightly different days from year to year. This is slightly inconvenient when it comes to comparing seasons, as each astronomical season will vary in length each year, and their start dates don’t fall neatly on the Gregorian calendar. Thus, the meteorological system divides the year into 3-month segments starting on the 1st March, 1st June, 1st September and 1st December for Spring, Summer, Autumn and Winter respectively. These groupings are based on the average temperatures for each season, with spring signifying a “warming-up” between the cold months of winter and the warm summer months.

    However, the meteorological definition of the seasons has its flaws too. Some studies have suggested that spring-time flowers have been blooming days earlier than historically noted, as may have been seen in parts of the country this year following a relatively mild and wet winter. On the other hand, it appears that we haven’t yet shaken off the shackles of the current winter, with many parts of the UK set to experience at least one frosty night this weekend.

    So, much like a physical spring, the season has a tendency to jump about a bit!

    By: Laura Caldwell