Minecraft wiki entry for Daylight_cycle, associated text: All blocks that are in direct vertical view of the sky receive sunlight at the internal sky-light level 15, which is the maximum. Sunlight provides ample light for the growth of saplings, grass blocks and crops. Most undead mobs (including zombies and skeletons) exposed to direct sunlight (and are not in shade, in water, or wearing helmets) are set on fire. Additionally, sunlight renders spiders neutral, unless they are currently chasing a player, and any endermen exposed to sunlight teleport randomly when near the player and randomly become neutral if having been aggressive for at least 30 seconds.