Perihelion is a term used in astronomy to describe the point in Earth's elliptical orbit around the Sun where the distance between the two bodies is at its minimum. The word "perihelion" comes from the Greek words "peri," meaning "near," and "helios," meaning "Sun." At this point, Earth is approximately 91.5 million miles (147 million kilometers) away from the Sun.
Earth is tilted at an angle of 23.5 degrees. During January, the Northern Hemisphere is tilted away from the sun. This means solar rays hit the north at a shallow angle, spreading the energy over a larger area and providing less concentrated heat. Additionally, the days are shorter, providing less time for the atmosphere to warm up. when earth is closest to the sun