The period when the seasons change is critical to the evolution and continuation of life on the planet. These periods are occasion for changes in animal behavior and affect the life cycles of plants as well.

Why the Seasons Occur

This change happens because of the Earth’s evolution around the Sun. As the Earth spins, its axis tilts on one side. The axis is the imaginary line running north / south of the planet. It is the line that veers when the Earth rotates. The result is that one half is closer to the Sun and the other is further away.

These halves are divided by the equator. This is a line that runs around the Earth. The one at the top is the Northern Hemisphere and at the bottom is the Southern Hemisphere. When the seasons change, it is due to a hemisphere’s proximity or distance to the Sun.

Duration and Period

If the Northern Hemisphere is near the Sun, it is summer. If it is on the other side, it turns to winter. When the hemispheres are the same distance from the Sun, spring and autumn / fall take place.

Summer usually begins in June in the Northern Hemisphere and lasts until August or September. Winter starts in December and goes on until March. Autumn starts in September while spring takes place after winter. The dates for their occurrences are of course opposite in the Southern Hemisphere.

What Happens When the Seasons Change

During winter season most animals go into hibernation or migration. Among bears and reptiles it is the time they “go to sleep” and will emerge after the season. Beavers and raccoons consume the food supplies that they collected. Most plants and flowers also perish at this time.

The spring season follows. The flowers and plants start to bloom, and the leaves start to reappear on trees. The excessive rainfall or snow begins to melt. The birds that have migrated return to their nests and nurture for their young.

Animal activity reaches its peak in the summertime. The activity is not limited to animals and plants. It most cultures and countries, it’s a time when people go to play sports or head to the movies. It is the time when temperatures are at its highest.

The final period when the seasons change is autumn. It is usually the harvest time. Trees also undergo change. They shed foliage and the animals start to collect food. When autumn ends, winter will start and the cycle will begin again.

Dry and Wet Season

In some parts of the world (especially Southeast Asia) there is only the dry and wet season. The dry season takes place from November to May. The rainy season goes on from June to September. In some regions there is also a “cool but dry” season lasting from October to February.

The times when the seasons change signal altering patterns of behavior among animals and people. By understanding how they work it becomes easier to recognize animal behavior.

The period when winter starts differ in the Northern and Southern Hemisphere. In the Northern Hemisphere it is from December 20 up to March 21. In the Southern Hemisphere this would be around June 20 and culminates on September 22.

The beginning and end dates may vary a day or two. The coldest month in the Northern Hemisphere is usually January.

Characteristics

The most prevalent trait is cold weather. In countries like the US and Canada, the season is marked by the presence of heavy snowfall. In other countries it is characterized by rain instead. The season is also marked by typhoons and hurricanes in some parts of Asia. When winter starts the nights are longer too. The afternoons are longer and much colder.

Other weather phenomenon associated with this season is ice fog. This can take place when the temperatures go below -25 C or – 20 F. This phenomenon usually takes place in the Northern Hemisphere.

Effect on Animals

Animal behavior is greatly affected by the coming season. One of the most common traits is that of migration. This can be seen in a lot of animals particularly birds. Some species of butterflies also migrate when the season approaches. The migration does not occur among all bird species though.

When winter starts some animals go into hibernation. What these animals do is sleep during the period. This behavior is most apparent in bears. However it can also be seen in other species like snakes, bats and other reptiles.

Changes in animal behavior include accumulation of food. This activity can be seen among squirrels raccoons and beavers. Another sign of the coming season is that the color or fur changes. This can be seen in the snowshoe hare, the white tailed jackrabbit and ptarmigan.

Effects on Plants

With the exception of the flowering plum, almost all plants and flowers perish during this season. Trees lose their leaves and some branches as well. Even when winter starts, the trees will be able to grow leaves again because their roots survive.

Duration

Although the period for the season is defined in the Northern and Southern Hemispheres, countries have their own calendars and occasion that state when the season “officially” begins. For instance, in Ireland the season officially commences on the first day of November. In other European countries the season commences on the 11th of November. In China the official date is on the 7th, also in the same month.

In Culture and the Arts

In mythology, the season is traditionally associated with death, spring being the resurrection. This is exemplified in the Greek tale of Persephone. The same theme is used in the poems of Robert Frost and the works of C.S. Lewis and Vivaldi.

Recent studies have also shown that some people are susceptible to disorders brought by the coming of the season. These cases are termed seasonal affective disorders or SAD.

The time when winter starts is different in various parts of the world. Due to the changing climates, the occurrence and duration of the season may gradually be also subject to change soon.

The first day of autumn / fall is September 22 in the Northern Hemisphere. In the Southern Hemisphere it is on March 20. Using astronomical calculations however, it would fall anytime between September 1 to 15. The difference is due to the weather. They tend to lag behind the celestial calculations.

Changes in Temperature

As it follows summer, the most noticeable event will be the drop in temperature. This doesn’t suggest a sudden fall. It is rather a gradual decrease, especially in the mornings. In Florida for example, the mornings will be cooler around mid or late September. But it can also go up a little come October. The full extent of autumn usually doesn’t become evident until well into October in the US.

Changes in the Air

The first day of autumn can also be felt through the air. The heat from the Sun starts to lessen. Going around the city you’ll see the shadows get longer, indicating the coming shorter days. Nature observers also note that the sky turns very blue. The air may have a dry feel. In addition the lowering temperature produces an earthly and pleasant smell among sycamore leaves.

Leaves Changing Color

Other indications of the changing season are the leaves. The vibrant greens that summer produces will turn into varying shades of red, sand and yellow.

In parts of Canada, there’s usually a breeze or chill. This occurs even though the Sun is still very bright. The chill continues to the nighttime. It can also produce some interesting colors in the sky. In some cases the first day of autumn can give the Moon a slightly reddish glow.

Animals

Animal activities also change during the fall. Scrub birds will screech a lot while stocking up food. If there are squirrels around the area, you’ll see them gathering their food supplies as well. It’s not unusual to see them take large amounts of acorn. A lot of squirrels also store nuts.

A lot of animals store food during this period, knowing that winter is approaching. Aside from squirrels, chipmunks also store food. Among birds, it’s customary to gather food for the winter as well. There are also some cats whose fur starts to get thicker in anticipation of the winter.

Signs among People

Some people start to wear jackets and sweaters on the first day of autumn. It’s also customary for some to put up small ornaments indicative of the season.

In the past, fall was associated with the harvesting of fruits. In paintings, the season is often depicted with people gathering fruits and vegetables. Cabbage and pumpkin are particularly ripe at this time.

Other Indications

Birds of different species will usually gather around a single tree as they start to get ready for the cold months. The trees themselves give out signs, most notably turning into a rich brown. Martins, swifts, and other colorful birds also come together. It makes trips to the park at this time very pleasant.

The fall has been associated with melancholy times. But as the signs of the first day of autumn shows, it is actually an enjoyable period.