årstider

Årstider, or the four seasons, refer to the division of the year based on periodic changes in weather, daylight, and the appearance of flora and fauna. These seasonal changes are primarily caused by Earth's axial tilt and its orbit around the Sun, resulting in variations in solar exposure and temperature across different parts of the planet.

The four traditional seasons are spring, summer, autumn, and winter. In many temperate climates, spring typically occurs between March and May, marked by warming temperatures, blooming plants, and longer daylight hours. Summer, spanning June to August, is characterized by the longest days of the year, high temperatures, and lush vegetation. Autumn, from September to November, features falling leaves, cooler weather, and shorter days as daylight gradually decreases. Winter, lasting from December to February, is the coldest season, often accompanied by snow or frost, depending on the region.

The timing and definition of seasons can vary by region and cultural context. In some areas, such as near the equator, seasonal changes are less pronounced, while in polar regions, seasons are defined by the presence or absence of sunlight rather than temperature. Additionally, certain cultures recognize more than four seasons, such as the six-season system used in some East Asian traditions, which includes intermediate periods like late summer and early autumn.

Climate change has also influenced seasonal patterns, leading to shifts in temperature extremes, precipitation levels, and the timing of seasonal events like flowering or migration. Understanding and monitoring these changes is important for agriculture, ecology, and daily life.