冰雹凭什么能长到垒球那么大?云里开了「过山车」吗?
How can hailstones grow to baseball size — is there a roller coaster inside the storm?
确实有,那就是超级单体里倾斜的上升气流。雹胚被气流托举进入过冷水滴区,撞冻上一层冰后被甩出上升流或因重力下坠,再被另一支气流重新抬升,往复经历干湿交替生长:湿层冻结慢形成透明冰,干层快冻夹带气泡成乳白冰,层层年轮记录了它在云中的每一圈行程。垒球大小的冰雹要求上升气流速度超过每秒50米。1970年堪萨斯州科菲维尔落下一颗重约760克的冰雹,曾长期保持美国重量纪录。
There is one — the tilted updraft of a supercell. An embryo gets lofted into the supercooled droplets, accretes an ice layer, gets ejected or falls out, then is recaptured and lifted again; alternating wet and dry growth leaves clear and milky ice rings recording every lap through the storm. Softball-size hail demands updrafts exceeding fifty meters per second. The stone of roughly 760 grams that fell on Coffeyville, Kansas in 1970 held the U.S. weight record for decades.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Browning, Foote,《Airflow and hail growth in supercell storms and some implications for hail suppression》,Quarterly Journal of the Royal Meteorological Society,1976 (DOI: 10.1002/qj.49710243303)
Browning, Foote, 'Airflow and hail growth in supercell storms and some implications for hail suppression', Quarterly Journal of the Royal Meteorological Society, 1976, DOI: 10.1002/qj.49710243303
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1002/qj.49710243303
#冰雹 #上升气流 #过冷水
台风为什么都诞生在热带海面,却从不跨过赤道去南半球串门?
Why are typhoons born over warm tropical seas yet never cross the equator south?
三个条件缺一不可:海表温度超过26.5摄氏度并提供蒸发潜热;一定的初始旋转扰动;以及足够的科氏力让气流开始螺旋汇聚。赤道恰恰是科氏力为零的地带,扰动在那里无法组织成旋涡,所以台风生成区分布在南北纬5度以上;西太平洋的暖水池最大最持久,因此西北太平洋贡献了全球三分之一的台风,也是唯一能出现超强台风级别的海域。登陆后切断水汽补给、摩擦增大,风暴便迅速衰竭——这就是台风怕陆地的原理。
Three ingredients must coexist: sea surface above 26.5 degrees Celsius feeding evaporation, some initial spin disturbance, and enough Coriolis force to organize inflow into a vortex. The equator itself has zero Coriolis force, so no cyclone organizes there — genesis zones sit beyond five degrees latitude. The western Pacific warm pool is largest and longest-lived, spawning a third of all typhoons including the strongest superstorms. Landfall cuts moisture and raises friction, so storms decay fast ashore.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Emanuel,《Tropical Cyclones》,Annual Review of Earth and Planetary Sciences,2003 (DOI: 10.1146/annurev.earth.31.100901.141259)
K. Emanuel, 'Tropical Cyclones', Annual Review of Earth and Planetary Sciences, 2003, DOI: 10.1146/annurev.earth.31.100901.141259
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1146/annurev.earth.31.100901.141259
#台风生成 #科氏力 #暖水池