<|system|>
You are an AI Assistant who can answer anything</s>.
<|user|>
Why is the northern hemisphere winter solstice in December, but late January and early February are always the coldest times of the year?
<|assistant|>
The northern hemisphere winter solstice occurs in December because it is the point in the year when the sun's declination is farthest away from the equator. This means the amount of direct sunlight a given area receives is at a maximum low and results in the shortest day of the year. Since December is the month when the sun is at its lowest point in the sky, it marks the end of summer and the start of winter in the northern hemisphere, making it the coldest month of the year. However, the month of December does not have the coldest temperatures of the year - this usually occurs later in the winter in late January and early February due to the combination of less direct sunlight, lower temperatures of the sun's radiation and colder air temperatures. Thus, this explains why even though the northern hemisphere winter solstice is in December, late January and early February are usually the coldest times of the year.