The astronomical start of autumn is defined by the autumnal equinox, which is the day when the sun crosses the celestial equator, moving southwards into the Southern Hemisphere. The exact date and time of the equinox varies from year to year, but it generally occurs around September 22 or 23 in the Northern Hemisphere and March 20 or 21 in the Southern Hemisphere.
Autumn is a season of change and transition. The days become shorter, and the nights become longer. The deciduous trees begin to drop their leaves, changing the landscape from a lush green to a more muted palette of red, orange, and yellow. The weather can be unpredictable, with a mix of sunny days and rain showers.
Autumn is a time to harvest crops and prepare for the coming winter. It is also a time to enjoy the beauty of the natural world and spend time with loved ones.
Here are some of the key characteristics of autumn:
* Changes in daylight hours: The days begin to get shorter, and the nights become longer. The decrease in daylight hours is caused by the Earth's tilt on its axis, which means that the amount of sunlight that reaches the Northern Hemisphere decreases as the year progresses.
* Changing weather: The weather in autumn can be unpredictable, with a mix of sunny days and rain showers. The temperature also begins to drop as the year progresses.
* Fall foliage: The leaves of deciduous trees begin to change color and fall off. The changing colors of the leaves are caused by a decrease in chlorophyll, the green pigment that plants use to convert sunlight into energy.
* Harvesting: Autumn is a time to harvest crops, such as corn, wheat, and soybeans. The harvest is a time to celebrate the bounty of the earth and to prepare for the coming winter.
* Recreation: Autumn is a popular time for outdoor activities, such as hiking, camping, and fishing. The weather is often mild, and the scenery is beautiful.