2.3  Five  Reasons for Seasons
Channel: Dr. No Knows Weather
Date: 2020-06-06

This video lecture is part of the book: Weather, Climate , and Beyond: An introduction to Physical Geography: https://tophat.com/marketplace/science-&-math/earth-sciences/full-course/weather-climate-and-beyond-an-introduction-to-physical-geography-third-edition/3477/246759/

Seasonality

Rotation
Revolves
Sphericity
Earth's Axis Tilt
Axial parallelism

Seasonality
Changes in the Sun's position above the horizon during the year are defined as seasonality. You might have noticed the Sun reaches the maximum elevation in the sky at local noon time and during the year that elevation gets lower during the winter season and higher in the summer. The angle between the horizon and the sun is called Sun altitude. If the Sun is directly overhead, the subsolar point, the sun altitude is 90°, and we receive the maximum solar energy at that location. The subsolar point travels from 23.5° N to 23.5° S and its latitude on any given day is known as the Sun's declination. All those changes in the Sun's position in the sky relate to the latitude during the year and affect the day length. 

The regular changes in day length, Sun altitude, and declination result from astronomical factors such as rotation, Earth's revolution, Earth's axis inclinations and parallelism. Combined they are the five reasons for the seasons.