What Happens in Spring?
From 20 March onwards in the northern hemisphere, the hours of daylight get longer and longer until summer, when you will notice that it is still light at bedtime. So when summer begins on 21 June there are over 16 hours of daylight and under 8 hours of darkness.
The reason for the days getting longer is because our country of the United Kingdom, along with others in the northern hemisphere is tilting more and more towards the sun. As the sun's rays reach us more directly the days get warmer as well as longer.