地形
环礁
环礁是圆形的低海拔岛屿，通常环绕着礁湖。
color = terrain_atoll
can_freeze_over = no
movement_cost = 1.0
weather_front_strength_change_percent = 0
weather_cyclone_strength_change_percent = 0
weather_tornado_strength_change_percent = 0
audio_tags = {
masDataTopologyElevation = 0
masDataTopologyOcean = 1
masDataTopologyCoast = 1
}
debug_color = hsv360 { 195 70 100 }