What Is Winter?
Winter is the season that comes after fall and before spring. Winter is usually the coldest time of year and in some places, it brings freezing temperatures, snow, and ice with it. Even places that don't get snow or freezing cold weather still have a winter season. Here are a few ways to tell that it's winter, other than snow and cold:
- The days are shorter and the nights are longer than during any other season. Today (December 21st) is the first official day of winter, because it is the shortest day of the whole year!
- The sun doesn't shine as warmly on the earth during the winter, even on the brightest days.
- Trees and plants usually go dormant (like they're sleeping) or else die so when you look outside, you'll see more brown than green.
- Winter is a wet season, with lots of rain or snow.
The changes that winter brings affect people, animals, plants, and trees alike. Trees and plants go dormant to live through the cold and some animals hibernate while other store up food in the fall to eat during the winter when it gets harder to find food. To learn more, check out our newsletter about Hibernation. Some animals adapt to the change in weather by growing a white colored winter coat of fur to blend in with snow. Many animals eat different foods in the winter than during the rest of the year. Squirrels and mice gather food like nuts and seeds in the fall and save them in their nests to eat in the winter, and others like deer eat twigs and bark when it's hard to find other things to eat. These are ways that animals can adapt to stay alive and active during the coldest times of the year.
Why Do We Have Winter?
We have seasons because of the way that the earth moves around the sun. The earth orbits the sun along an egg-shaped path, just like all of the other planets do. It takes a whole year, or 365 days, for the earth to go all the way around the sun one time. The earth is also tilted. It is always tilted in the same direction, so only part of the earth can be facing the sun at a time. The part of the earth that is tilted farthest away from the sun gets winter (because it is farther away from the sun) while the part of the earth that is towards the sun has summer (it is facing the sun more directly). The earth also spins around (like a top) while it is moving around the sun! It spins around one full time in a day. You can learn more about the planets and their orbits here.
Have you heard of the equator? It is an imaginary line around the middle of the earth that divides earth into two halves, a northern half and a southern half. While it is winter for the top half in places like North America and Europe, it is summer for the bottom half in places like Australia and South Africa! The sun shines directly on the equator all year, so how warm or cold your seasons are depends on how far away you live from the equator. If you live close to the equator, you probably don't experience very big changes in temperature when the seasons change. If you live a little farther away from the equator though, you probably experience warmer temperatures in the summer and cooler ones in the winter (when the part of the earth you live in is tilted away from the sun). You can see how sunlight changes during the winter with a flashlight in a dark room. Shine the flashlight onto the wall and notice how it makes a bright circle of light. Without moving the flashlight any closer or farther away from the wall, turn it a little so that the light shines on the wall at an angle. Now the beam of light covers more of the wall, but it doesn't look as bright or strong as it did when you held it straight (look especially at the edge of the circle farthest away from the flashlight). During winter, the sunlight has to stretch over more of the earth to get to us, so when the light does get there, it isn't as strong as when it is shining directly, like during summer.
Birds In Winter
Many birds fly south to warmer places for the winter. This is called migration. When snow starts falling and lakes and rivers begin to freeze, it gets harder for many birds to find food, so they start traveling south to places where they can find food more easily. They will head back to their summer homes to build nests and lay eggs when spring comes. Other animals migrate, too. Did you know that even Monarch butterflies, sea turtles, and salmon (a type of fish) migrate?
Check out our winter science projects for some fun cold-weather science ideas!