The variation in the angle at which sunlight strikes different latitudes on Earth is primarily caused by the tilt of the Earth's axis and its spherical shape. Here are the key factors:
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Axial Tilt: The Earth is tilted on its axis at an angle of about 23.5 degrees. This tilt is responsible for the changing angle of sunlight as the Earth orbits the Sun throughout the year. When one hemisphere is tilted toward the Sun, it receives sunlight more directly (at a higher angle), while the other hemisphere, tilted away, receives sunlight at a lower angle.
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Spherical Shape of the Earth: The Earth is not flat; it is a sphere. This means that as you move away from the equator toward the poles, the surface area that sunlight must cover increases, causing the sunlight to spread over a larger area. As a result, the same amount of sunlight is less concentrated at higher latitudes compared to the equator, where the sunlight strikes more directly.
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Seasons: Due to the axial tilt, different parts of the Earth receive varying amounts of sunlight throughout the year, resulting in seasons. For example, during the summer solstice, the northern hemisphere is tilted toward the Sun, causing it to have longer days and higher angles of sunlight, while the southern hemisphere experiences shorter days and lower angles of sunlight, leading to winter.
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Latitude: The Earth's latitude plays a critical role in the angle of sunlight. At the equator (0 degrees latitude), sunlight hits the Earth at nearly a 90-degree angle throughout the year, leading to consistent, warm temperatures. As one moves toward the poles (90 degrees north or south), the sunlight strikes at increasingly shallow angles, resulting in cooler temperatures and varying lengths of day and night.
These factors collectively lead to the variations in the angle at which sunlight hits different latitudes, influencing climate, weather patterns, and ecosystems around the globe.