Understanding what causes seasons, and the effects they can have on magic, is important to the daily lives of every wizard and witch. In a nutshell, the seasons are caused by the tilt of the Earth’s axis, and the revolution of the Earth around the Sun. The tilt of the Earth’s axis has a larger impact on the weather than any other natural or manmade phenomenon. The Earth’s axis has a tilt of 23 degrees, 27 minutes (approximately 23.45 degrees). This means at any time throughout the year, one hemisphere of the Earth is tilted closer to the Sun than the other, causing it to receive more direct sunlight. During summer in the northern hemisphere (June, July, August), the northern hemisphere is tilting towards the Sun, and the southern hemisphere is tilting away from the Sun. This means the northern hemisphere is receiving more direct sunlight than the southern hemisphere. The opposite occurs during winter in the northern hemisphere (December, January, February). Then, the southern hemisphere is tilting towards the Sun, and the northern hemisphere is tilted away, causing the southern hemisphere to receive more direct sunlight than the northern hemisphere. That is why, when it is summer in the northern half of the planet, it is winter in the southern half, and vice versa.

4a. What Causes Seasons?

The reason the part of the Earth tilted towards the Sun has higher temperatures than the part tilted away has to do with the angle at which sunlight strikes the Earth. For example, when the southern hemisphere is tilted away from the Sun, the Sun strikes that hemisphere at a shallower angle than when that hemisphere is tilted towards the Sun. When a hemisphere is tilted away from the Sun, the same amount of sunlight is distributed over a much larger area; therefore, each place the sunlight hits will get less heat than if the sunlight were more concentrated. As a result, when a hemisphere is tilted away from the Sun, that hemisphere experiences winter. If the southern hemisphere is tilted away from the Sun, it will be winter in the southern hemisphere, and summer in the northern hemisphere.

The number of hours of sunlight received in one day is also affected by the tilt of the Earth’s axis, for the same reason. When a hemisphere is tilted away from the Earth, the shallower angle between the Earth and the Sun means the sunlight hits the Earth for a shorter period of time than when the angle is deeper.

There is a common misconception that the seasons occur because of the Earth’s physical distance from the Sun. This was actually disproved by the ancient Greek wizard Hipparchus, a master in the Muggle field of trigonometry, in 149 BCE. Although the Earth does orbit the Sun in an ellipse, its path is still very nearly circular, so the Earth’s orbit has a negligible impact on the seasons. Indeed, when the Earth is closest to the Sun, the northern hemisphere is experiencing winter, whilst the southern hemisphere is experiencing summer. If it were only the Earth’s distance from the Sun that caused the seasons, then the entire planet would experience summer when the Earth was closest to the Sun, and winter when the Earth was at its greatest distance from the Sun. That is not the case.

The four seasons are marked by solstices and equinoxes. The point at which the Sun is at its highest in the sky, as seen from the North or South Pole, is called a solstice. Solstices occur twice a year, once in June, when the northern hemisphere is tilted at its maximum angle towards the Sun and the southern hemisphere is tilted at its maximum angle away from the Sun, and once in December, when the opposite occurs. Spring and fall occur during periods of transition in the tilt of the Earth’s axis, between the two solstices. For example, during spring in the northern hemisphere, the Earth’s axis is increasing its tilt towards the Sun, causing the hours of daylight to increase up until the summer solstice, when the Sun is highest in the sky. During spring and fall, a point in time occurs when the Sun is closest to being directly over the equator, and the lengths of night and day are nearly equal (12 hours each) almost everywhere on the planet. These two points in time are the vernal equinox (in March), and the autumnal equinox (in September), and these equinoxes mark the official start of Spring and Fall. (See Chapter 8, Solstices and Equinoxes).

4b. Spring

Spring is a season of new life and renewal. Spring occurs at different times of the year in different places. In general, it occurs over the three months following the three coldest months of the year: March, April, and May, in the northern hemisphere; September, October and November, in the southern hemisphere. However, certain cultures consider spring to start at different times. An odd Muggle tradition in the United States is that every February 2nd, they check to see whether or not a groundhog emerging from its hole can see its shadow. If the groundhog cannot see its shadow, spring will come early, whilst if it can, there will be six more weeks of winter. This seems to be a primitive Muggle form of Divination, however, and the groundhog is rarely correct in its predictions. In certain places, spring can cause some erratic weather patterns, such as flooding and tornadoes, but for the most part, it is a season of growing warmth. Plants start to bloom and baby animals are born. This is why the spring season is so important to wizards. It is the prime time of the year for herbologists to begin planting. It is also wise to be careful, as in spring there are many young dragons and other dangerous creatures gallivanting about, and mothers will ferociously defend their young from even perceived harm.

4c. Summer

Summer is the season that corresponds to the three hottest months of the year, approximately June, July, and August, in the northern hemisphere, and December, January, and February, in the southern hemisphere. However, in tropical regions, summer is the wet season, bringing lots of rain. Summer contains the longest days of the year. For Muggles, summer brings a break from school, and many families spend the time vacationing. Wizard children also have time off from school, and although many go on holidays with their families, one is much more likely to find young witches and wizards playing a game of Quidditch in the yard, or complaining about being unable to use magic outside of school. Herbologists must pay special attention to their plants during this season, as plants are prone to wilt in the hot summer heat. For those interested in astronomy, summer is a perfect time to get away from the lights of Muggle cities and look at the stars. One of the best meteor showers of the year, the Perseids meteor shower, occurs in the northern hemisphere from mid-July to mid-August each year. At its peak, it is possible to see up to eighty meteors, colloquially called ‘shooting stars’ by Muggles, in an hour.

4d. Fall

Fall, or autumn, is the season of the year when the leaves begin to turn Colour and drop from the trees (at least in colder climates). It consists of the three months of the year after the three warmest months, usually about September, October, and November, in the northern hemisphere, and March, April, and May, in the southern hemisphere. During fall, the nights start to get longer, and the days get shorter. Fall has always been a season of harvest, and for this reason, it holds particular significance for herbologists. The majority of plants will have matured by this time, and both herbologists and Muggle farmers alike are kept very busy bringing in their crops. A very strange Muggle tradition in some countries is associated with Halloween, or All Hallow’s Eve. This involves Muggle children dressing up as witches, wizards, vampires, and ghosts, and going door-to-door to collect treats. Muggles have many theories about where this custom began, but in the wizarding community, rumor suggests it was started by one of the first American wizards, shortly after the Statute of Secrecy was signed in 1689. It is said that he wanted a day where witches and wizards could dress as they pleased, without arousing the curiosity of Muggles. Of course, wizards also celebrate Halloween, which is, in fact, famous as the day the First Wizarding War ended, after the disappearance of Voldemort. From an astrological standpoint, there are a number of meteor showers that occur in various places around the world throughout the autumn months. Fall also is known for the Harvest Moon, the Full Moon closest to the fall equinox. On this night, the Moon appears much larger and brighter than usual. It also might look red, due to the scattering of light in the atmosphere. The night of the Harvest Moon is especially challenging for werewolves, and there are more incidences of werewolf bites on this night than during other Full Moons throughout the year. It seems that the closeness of the Moon causes the werewolves to crave flesh more than usual.

4e. Winter

Winter is the coldest season of the year. It consists of the months of December, January, and February, in the northern hemisphere, and June, July, and August, in the southern hemisphere. A number of holidays celebrated by both magical and non-magical communities occur throughout winter, including Christmas and Valentine’s Day. Winter has the shortest days of the year. In the northern hemisphere, winter may be associated with large amounts of snow and ice. It is recommended that witches and wizards avoid travelling by broomstick during the winter months, as visibility can be very low, and the possibility of frostbite high. Many animals migrate to warmer climates during winter, so the chance of seeing any magical creatures around is diminished. This is understandable, as the cold and dark of winter in some places can have adverse effects on both humans and non-humans. Excess cold actually can affect one’s ability to perform magic. For example, the cold and dark of winter can bring on depression in some people. This can keep them from performing magic properly, as emotions can play a role in the power or effectiveness of a spell. When one is depressed, one also may be less able to resist spells such as the Imperius curse; to perform Occlumency; and even to execute non-verbal spells.

4f. Applications

Now that you know what causes the seasons, and have a description of their typical characteristics, you should keep them in mind as you go about your daily life. Watch for the lengthening and shortening of the days as signs of the changing seasons. Keep track of weather patterns and the regular cycles of plants and animals. All of this is necessary to truly understand the natural magic that controls the movements of the planets, and even the systems of nature here on Earth.