Due to Sporadic E propagation during the late spring and most of the summer, regardless of sunspot numbers, afternoon short band openings into small geographic areas of up to 1500 km occur.
由于在晚春和夏季大部分时间的零星E传播，无论太阳黑子数量如何，下午短距离开放进入长达1500公里的小地理区域。