More time in the light
Why Are Days Longer in Summer?
The tilt swings your part of Earth through more of the sunlit half.
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Step 1 of 5
A day is always one full spin.
By the stars a spin takes 23 h 56 min; the extra four catch the Sun up. Earth takes 24 hours to turn once, every day of the year. Summer does not slow the spin down — the spin is the one thing that never changes.
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Step 2 of 5
Half of Earth is lit at any moment.
The dividing line between day and night sweeps around the planet. Your day length is simply how long your spin keeps you on the lit side.
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Step 3 of 5
The tilt moves that dividing line.
Earth's 23-degree lean means the day-night line does not run straight through the poles. It sits at an angle, cutting the northern half unevenly.
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Step 4 of 5
Leaning toward the Sun means a longer arc in the light.
In summer your latitude spends more of its circle on the sunlit side. You are literally carried through more daylight before you rotate out of it.
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Step 5 of 5
It gets extreme at the poles.
The further from the equator, the harder the seasons swing the daylight. Above the Arctic Circle in midsummer, your circle never crosses into the dark half at all. The Sun circles the sky without setting for weeks.
Two days a year — the equinoxes — everywhere on Earth gets almost exactly 12 hours of daylight.
The short version
The spin never changes: 24 hours, every day of the year. What the 23-degree tilt changes is how much of that spin you spend on the lit side — which above the Arctic Circle can mean all of it.
Try it yourself
Draw a circle around an orange near the top, then tilt the orange toward a lamp. Watch how much of that circle is in the light.