Everywhere gets the same amount of daylight over the year. But where the sun gets higher in the sky, you get more heat from it per unit area - that's why it never gets very warm at the Poles, even though you get 24 hours of daylight in the summer - the sun is never more than 23 degrees above the horizon.
The amount of heat per unit area goes as the sine of the sun's elevation, so varies more at low elevations - at 30 degrees you get half (not a third) of the intensity you get at 90. As for absorption by the atmosphere, depending on what value you use for the thickness of the atmosphere, geometry gives values of around ten times as much absorption when the sun is on the horizon compared to when it is overhead.