🌍 Seasons and climate

Earth spins on an axis that is tilted at an angle, not straight up and down, and that tilt stays pointed in the same direction all year as Earth travels around the sun, so different parts of the planet lean toward or away from the sun at different times. It is the tilt, not distance from the sun, that causes seasons, in fact Earth is actually slightly closer to the sun during part of the northern winter. The tilt is also why the northern and southern halves of Earth have opposite seasons at the very same time.

Weather is what is happening in the sky right now or this week, sunny, rainy, hot or cold, while climate is the average pattern of weather a place usually has over many years. A single unusually cold day does not mean the climate is changing, just like one hot summer does not prove anything about long-term patterns, climate is about the bigger, longer picture. Scientists study climate by looking at decades or even centuries of weather records, not just a few days or weeks.

A place's typical temperature depends heavily on how close it is to the equator, since areas near the equator get more direct, intense sunlight year round, while places near the poles get sunlight at a much lower, weaker angle. Nearby oceans, mountains, and elevation matter too, coastal areas tend to have milder temperatures than places deep inland, and high mountain areas stay cooler because thinner air holds less heat. All these factors combine to create the wide variety of climates found across the planet, from steamy rainforests to frozen tundra.

How much rain a place gets depends a lot on where its air comes from, air that travels over warm oceans picks up lots of moisture, while air that has already dropped its rain crossing tall mountains arrives dry on the other side, creating what is called a rain shadow. Places near warm, moist air sources, like tropical coastlines, tend to get drenched regularly, while places deep inland or behind mountain ranges often stay dry for most of the year. This is exactly why a desert can sit surprisingly close to a lush, rainy region, just on the opposite side of a mountain range.