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How Earth’s Tilt Makes January’s Days Short and Cold

(CONVERT) – On the equator, official winter starting in December. But in many areas, January is when it really counts. Atmospheric Scientist Deanna Therefore explains how weather and climate factors combine to create winter conditions at the turn of the year.

How does Earth’s orbit affect our daylight and temperature?

As the Earth revolves around the sun, it rotates on an axis – the image of a stick passing through the Earth, from the North Pole to the South Pole. In the 24 hours it takes for the Earth to make one revolution on its axis, every point on its surface points toward the Sun for part of the time and away from it for part of the time. This is what causes daily changes in sunlight and temperature.

There are two other important factors: First, the Earth is round, although it not a perfect sphere. Second, its axis is tilted about 23.5 degrees relative to its path around the Sun. As a result, light falls directly on its equator but at an angle to the North and South poles.

When one of the poles faces the Sun more than the other, half of the planet receives more sunlight than the other, and in that hemisphere it’s summer. When that pole tilts away from the Sun, that half of the Earth gets less sunlight and it’s winter there.

The seasonal variation is most dramatic at the poles, where the variation in light is most extreme. During the summer, a pole receives 24 hours of sunlight and the Sun never sets. In winter, the sun never rises.

At the equator, which receives consistent direct sunlight, there is little variation in day length or year-round temperature. People who live in high and middle latitudes, closer to the poles, may have very different ideas about the seasons than people living in the tropics.

There’s an old saying, “As the days get longer, the colder it gets.” Why is it usually colder in January even though we have daylight?

It depends on where in the world you are and where your air is coming from.

The Earth’s surface continuously absorbs energy from the Sun and stores it as heat. It also radiates heat back into space. Whether the surface warms or cools depends on a balance between the amount of solar radiation the planet is absorbing and the amount of radiation traveling away.

But the Earth’s surface is not uniform. Soil usually heats and cools much faster than water. Water takes more energy to raise and lower its temperature, so it warms and cools more slowly. Because of this difference, water is a better heat carrier than land – especially large bodies of water, like the ocean. That’s why we tend to see a larger variation between warm and cold inland than in coastal areas.

The farther north you live, the longer it will take for the amount and intensity of daylight to begin to increase significantly in midwinter, as your position is tilted away from the Sun. Meanwhile, areas with little sunlight continue to radiate heat into space. As long as they receive less sunlight than they give off, they will continue to get colder. This is especially true on land, where heat is lost more easily than in water.

As the Earth rotates, air circulates around it in the atmosphere. If the air moving into your area is mostly coming from places like the Arctic that don’t get a lot of sun in the winter, you may be experiencing extreme cold fronts for a long time. That happens in the Great Plains and the Midwest as cold air descends from Canada.

But if your air encounters a body of water that keeps the temperature more uniform throughout the year, these changes can be dramatically lost. Seattle is blown against the ocean by winds, which is why it is so much warmer than Boston in the winter even though it is further north than Boston.

How quickly do we lose daylight before the summer solstice and gain it back after?

This depends a lot on your location. The closer you are to one of the poles, the faster the rate of change of daylight. That’s why Alaska can go from almost no daylight in the winter to almost no darkness in the summer.

Even for a particular location, variation is not constant from year to year. The slowest rate of daylight change at times – December in winter, June in summer – and fastest at equinox, in mid-March and mid-September. This shift occurs as the area on Earth that receives direct sunlight ranges from latitude 23.5 N – as far north as the equator as Miami – to latitude 23.5 S, southward. as far away from the equator as Asuncion, Paraguay.

What’s happening on the opposite side of the planet right now?

In terms of daylight, people on the other side of the planet are seeing the exact opposite of what we are seeing. Currently, they are at the peak of summer and are enjoying the greatest amount of daylight they will receive of the year. I research about Rock storm in Argentina and Indian Ocean Tropical Cyclone, and both of those warm-weather hurricane seasons are peaking right now.

But there is one key difference: The Southern Hemisphere has less land and more water than the Northern Hemisphere. Thanks to the influence of the southern oceans, land masses in the Southern Hemisphere tend to have extremely lower temperatures than land in the Northern Hemisphere.

So even though a position on the opposite side of the planet to your location may currently receive as much sunlight as your area in the summer, the weather there may be different from the summer conditions you are used to. But it can still be fun to imagine a warm summer breeze on the far side of Earth – especially in a snowy January.

The Conversation is an independent and non-profit source of news, analysis and commentary from academic experts. This article is republished from The Conversation under a Creative Commons license.

https://kfor.com/news/how-the-earths-tilt-creates-short-cold-january-days/ How Earth’s Tilt Makes January’s Days Short and Cold

JACLYN DIAZ

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