vuositasoisina

Vuositasoisina, or "yearly seasons," refers to the four traditional divisions of the year based on climatic and astronomical changes: spring, summer, autumn, and winter. These seasonal cycles are a natural phenomenon observed across many cultures and are primarily determined by Earth's axial tilt and orbit around the Sun. The timing and characteristics of each season vary depending on geographical location, with temperate regions experiencing distinct seasonal shifts, while tropical and polar areas may have more subtle or exaggerated variations.

In the Northern Hemisphere, spring typically begins around March 20–21 with the vernal equinox, summer follows around June 20–21 with the summer solstice, autumn starts around September 22–23 with the autumnal equinox, and winter begins around December 21–22 with the winter solstice. These dates mark the points where the Sun's apparent position relative to Earth shifts, influencing daylight duration and temperature.

Cultural and agricultural practices often revolve around seasonal changes. Many societies have developed traditions, festivals, or holidays tied to specific seasons, such as harvest celebrations in autumn or winter solstice observances. Additionally, seasonal shifts impact ecosystems, influencing animal behavior, plant growth cycles, and human activities like farming, tourism, and clothing choices.

In some regions, particularly near the equator, seasonal distinctions are less pronounced, with relatively stable temperatures and daylight throughout the year. Conversely, polar regions experience extreme seasonal variations, with long periods of daylight in summer and prolonged darkness in winter. The concept of seasonal change remains a fundamental aspect of Earth's climate and has shaped human perception of time and nature for millennia.