Seasonal ChangesAlthough most of you know what seasons are, we wanted to give you a quick overview. Seasons are all created because the Earth actually sits on a small tilt. If you put a stick through the planet and watched it spin, you would see that we spin 23.5 degrees off a straight up and down position. Since we are at a tilt, different parts of the planet are warmer during different times of the year. With the tilt, our year is broken up into four seasons.
SummerFor the northern hemisphere, summer is the warmest time of year. It's not because the planet is that much closer to the Sun, it's because the top part of the Earth is facing the Sun for a amount of time. The longest days of the year occur during the summer months. June is the time of the summer solstice, the longest day of the calendar year. The time of the solstice is determined by the location of the Sun. It is directly over the Tropic of Cancer on that longest day. Never forget about the southern hemisphere. During the longest day in the north, you will find the shortest day in the south. When there's a heat wave in the United States, it is probably snowing in South America. Summer events include high temperatures, longer days, droughts, and tropical cyclones.
Fall/AutumnThis is one of the two in-between seasons. During summer, the North Pole is leaning towards the Sun and the South Pole leans towards the Sun in winter. Fall sees the planets axis directly in line with the Sun. The Sun is directly over the Equator during the autumnal equinox (September) and heating the northern and southern hemispheres equally. As the northern hemisphere is moving towards shorter days and the cold winter, the southern hemisphere is watching the snows melt and the flowers bloom during their spring. Autumn events include leaves falling from trees, shorter days than summer, and harvesting summer crops.
WinterThis is the season where the Earth is tilted way from the Sun and the South Pole is getting all of the light. It's almost constant night during the cold nights in the North Pole. The South Pole is home to many research scientists who are taking advantage of the long days and warmer temperatures. Winter finds snows across North America and summer fires and drought across the interior of Australia. In December, the Earth hits its next marker when the winter solstice occurs. That shortest day of the year (for the north) happens when the Sun is directly over the Tropic of Capricorn at noon. From that point, everything starts to change again. Winter events include colder temperatures, snow and winter storms, the shortest days of the year, and the hibernation of some animals.
SpringAhh the last season. Spring is a time for rebirth and emerging from the short and cold days of winter. While the northern hemisphere sees spring from March through June, it is fall in the southern hemisphere. March is the time of the vernal equinox that signals the official start of spring. But in reality, plants and animals start spring as soon as the weather starts to warm up. For them it's not about calendars, it's about the weather changing. As far as the position of the planet, it is a bit of a mirror image to our position in autumn. The Sun is directly over the Equator during the equinox and the northern and southern hemispheres are receiving about the same amount of the Sun's energy. Spring events include blooms of wildflowers, new leaves on trees, warmer days that winter, and wetter weather (not snow).
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Arctic Melt Season Lengthening (NASA/GSFC Video)
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