Give two reasons why it's warmer in summer than in winter.

The tilt of Earth's axis is the angle between the planet's rotational axis and its orbital plane, and it is approximately 23.5 degrees. This axial tilt is critical in creating the seasons as we experience them. During summer, the hemisphere that is tilted towards the Sun receives more direct sunlight over a given area than it does in winter. This is because when a hemisphere is angled towards the Sun, the solar rays strike the surface more perpendicularly. This direct angle allows for concentrated sunlight which delivers more energy and heat to that part of Earth.

As the year progresses, the hemisphere that was tilted towards the Sun begins to tilt away, leading to cooler temperatures and eventually, winter. It's the axial tilt that causes the dramatic difference in temperature between the seasons rather than the Earth's distance from the Sun, which many people erroneously believe to be the primary cause of seasonal temperature changes.

Direct sunlight refers to the sun's rays that travel to Earth's surface without significant dispersion, meaning they hit the ground at a steeper angle; close to a 90-degree angle. When the sunlight's path through the atmosphere is shorter, the energy doesn't spread out as much and is more concentrated when it reaches the surface. This results in increased heating and, consequently, higher temperatures.

Intensity of Sunlight

During summer, the Sun is higher in the sky, and its rays have greater intensity due to the direct angle. In contrast, during winter, the Sun is lower in the sky, and its rays hit the Earth at a more oblique angle, which disperses the energy over a larger area and reduces the overall heating effect.

The importance of understanding direct sunlight lies in its impact on daily and seasonal temperatures. Not only does it affect our climate, but also ecosystem behaviors and the physical and psychological well-being of all living organisms on Earth.

Earth's orbit is the elliptical path that our planet takes around the Sun. Contrary to what some might assume, the distance from the Sun due to this elliptical orbit does not significantly affect seasonal temperature variations. Our planet is closest to the Sun in January during the Northern Hemisphere's winter, indicating that distance alone does not dictate seasonal warmth.

Orbital Eccentricity

Earth's orbital eccentricity, which is the measure of how much the orbit deviates from a perfect circle, has fluctuations over thousands of years and can contribute to long-term climate changes known as Milankovitch cycles. However, yearly seasonal changes are predominately governed by axial tilt rather than changes in Earth's distance from the Sun.

It is essential to recognize that it's the combination of Earth's axial tilt and the path it takes around the Sun that determines the intensity and distribution of sunlight received, shaping the seasonal weather patterns. Without Earth's specific orbit characteristics, our planet's climate would be drastically different, and life as we know it could be significantly altered.