Earth is closest to the Sun during their summer when they are tilted towards the Sun and this means they get 7% more solar radiation. Therefore you'd expect the southern hemisphere summer to be a lot warmer than the northern summer. Equatorial regions experience only small seasonal changes in temperature due to the relatively constant angle between these regions and the sun. The figure on the right shows how seasons are determined by the tilt of the earth's rotational axis and the orbit of the earth around the sun.

Equatorial regions experience only small seasonal changes in temperature due to the relatively constant angle between these regions and the sun. The figure on the right shows how seasons are determined by the tilt of the earth's rotational axis and the orbit of the earth around the sun. There are only small seasonal changes in temperature at lower latitudes with increasingly larger seasonal changes in temperature at higher latitudes. The polar vortex forms every winter because of the temperature difference between the equator and the poles. In the polar stratosphere, sunlight basically gets cut off during the late fall and early winter – and that makes it really cold, while the equator remains quite warm. Because of the Earth's approximately 23.5º tilt, the seasons in the Northern and Southern Hemispheres are reversed, about six months apart from each other. Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays. So, when the North Pole tilts toward the Sun, it's summer in the Northern Hemisphere and when the South Pole tilts toward the Sun, it's winter in the Northern Hemisphere. This is because they are on opposite sides of our planet. The earth tilting toward the Sun makes summer, and tilting away from the Sun makes winter. Both the Northern and Southern Hemisphere experience opposite season. Most of the area of the southern hemisphere is ocean. The oceans warm up in the summer and retain heat during the winter. The northern hemisphere has much more land mass which loses its heat quickly.The Northern Hemisphere contains more land, while the Southern Hemisphere has more oceans. During July the northern half of our planet tilts toward the sun, heating up the land, which warms up easier than the oceans. The elliptical orbit of the Earth places the Southern Hemisphere closer to the sun during its summer months than the Northern Hemisphere during its summer. This means that the summer sun in Australia is 7 to 10 percent stronger than similar latitudes in the Northern Hemisphere.

Sunlight hits the Earth most directly at the Equator. The curve of the Earth means that sunlight is spread over a wider area the further you move from the Equator. Sunlight hits a smaller surface area at the Equator so heats up quickly compared to the poles. Equatorial regions experience only small seasonal changes in temperature due to the relatively constant angle between these regions and the sun. The hemisphere tilted toward the sun also has more hours of daylight than the hemisphere that is tilted away from the sun. The combination of more direct rays of sunlight and more hours of daylight causes the hemisphere tilted toward the sun to receive more solar radiation and to have warmer temperatures. Because the Earth is nearly round, the equator receives direct light, and the poles receive slanted light, with a gradation in between. Due to the differential heating of the Earth's surface, it is always warmer at the equator than at the poles. Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays. So, when the North Pole tilts toward the Sun, it's summer in the Northern Hemisphere. And when the South Pole tilts toward the Sun, it's winter in the Northern Hemisphere. The most important reason why summers in the Southern Hemisphere are not warmer than summers in the Northern Hemisphere is that: over 80 percent of the southern Hemisphere is covered with water.