Question

Why is the temperature lower at night than during the day?

Answer 1

During the daytime the sun is out and shining which helps to warm the earth up.

During the night the sun has gone down and not shining so as a result of the sun not shining the earths temperature cools down and we have a lower temperature at night.

Also have you noticed on cloudy days with rain or just overcast days that those days are much cooler than they would be if it were sunny?

That's another reason.

The clouds are blocking out the sun and making the weather feel much cooler than it normally would when the sun would be shining.

Answer 2

The warmth of the earth comes from the suns energy and when that sun is down and not shining then the earth cannot get the energy from the sun to warm the earth.

Since the sun is not available to warm the earth during the night then it becomes cooler.

Then in the day the sun comes back out which warms the earth.

Also the reason it stays cold during the day in the winter is because the earth is tilted away further from the sun so the earth cannot be warmed up from the suns energy.

Then when spring and summer comes the earth gets tilted back closer to the sun so it warms up again.