As depicted by the Wikipedia image below, the amount of insolation depends on latitude and on the time of year.
Insolation changes with the seasons and also changes between day and night. In the image below, adapted from Wikipedia, latitude is on vertical axis and time of year is on horizontal axis. In the Arctic, insolation is at its highest at the June Solstice, i.e. June 21 for the year 2021. At this time of year, the sunlight has less distance to travel through the atmosphere, so less sunlight gets absorbed or scattered before reaching the ground.
|The June Solstice in 2021 occurred on June 21, 2021.|
In addition, the high sun angle produces long days. At this time of year, the sun does not set above the Arctic Circle, so solar radiation continues all day and night. During the months June and July, insolation in the Arctic is higher than anywhere else on Earth. How much sunlight reaches the surface further depends on weather conditions such as clouds.
• Insolation, solar irradiance