为什么对流降水与暴雨?- 江南体育网页版- - - - -地球科学堆江南电子竞技平台栈交换 最近30从www.hoelymoley.com 2023 - 07 - 07 - t15:25:44z //www.hoelymoley.com/feeds/question/16431 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/16431 2 为什么对流降水与暴雨? 肯Kutcel //www.hoelymoley.com/users/15303 2019 - 02年- 17 - t20:52:12z 2019 - 03 - 16 - t04:13:27z < p >为什么对流降水与暴雨?< / p > < p >根据维基百科页面< a href = " https://en.wikipedia.org/wiki/Atmospheric_convection " rel = " nofollow noreferrer " >大气对流< / >:“湿对流导致雷暴发展,这通常是负责整个世界”的恶劣天气。< / p > //www.hoelymoley.com/questions/16431/-/16464 # 16464 3 答案由gansub对流降水与暴雨是为什么呢? gansub //www.hoelymoley.com/users/1066 2019 - 03 - 14 - t12:51:01z 2019 - 03 - 16 - t04:13:27z < p >在我们继续下去之前是很有帮助的评论这个Q / A - < A href = " //www.hoelymoley.com/questions/5380/are-clouds-a-gas-liquid-and-or-solid " >云气体,液体,固体和/或?< / > < / p > < p >理解这个问题的关键是要意识到这是失踪的比较。并对流降水产生更重的降雨相比一些其他形式的降水吗? < / p > < p >当我们看不同类型的降水和各自的尺度上希望我们能明白为什么对流降水产生更重的降雨。< / p > < p >有两种形式的降水- < a href = " http://glossary.ametsoc.org/wiki/Convective_precipitation " rel = " nofollow noreferrer " >对流< / >和< a href = " http://glossary.ametsoc.org/wiki/Stratiform_precipitation_area " rel = " nofollow noreferrer " >层状< / >。< / p > < p >我将提供两种类型的降水的定义基于意味着大气的垂直速度的大小。所以平均垂直速度(从观察中获得)平均< a href = " http://glossary.ametsoc.org/wiki/Vertical_velocity " rel = " nofollow noreferrer " >垂直速度< / >在大气体积被研究(在这种情况下,云(s)的问题)。

So stratiform precipitation is defined as

$ w << V_{ice,typical} $ and $w > 0$. where w is the mean vertical velocity and $V_{ice,typical}$ is the terminal fall velocity of ice crystals and snow(typically in the range 1-3 m $s^{-1}$)

Convection precipitation is defined as

$ w \approx V_{ice,typical} $ and w is in the range 1-10 m $s^{-1}$ and sometimes exceeds the value of $V_{ice,typical}$

These definitions are due to Henry Houghton as shown from the reference - On Precipitation Mechanisms And Their Artificial Modification. Also stratiform precipitation occurs mostly from nimbostratus clouds and convective precipitation occurs from cumulonimbus clouds.

Now let us list the different types of instability in the atmosphere and the scales at which they evolve(any cloud has to form due to an instability in the atmosphere)

1) Conditional instability/Convective instability - (usually less than 10 km horizontally) and time scale - few minutes

2) Symmetric instability - ( 200 kms horizontally) and time scale - few hours

3) Baroclinic instability ( less than 2000 kms horizontally) and time scale - maximum 2-3 days.

Now let us match the speed of the vertical motions in the atmosphere with the scales at which a particular instability evolves. I am going to exclude symmetric instability from this discussion.

Frontal systems(baroclinic instability), systems affected by topographic lifting and large scale horizontal convergence produce stratiform precipitation and continuous rain. In this case growth occurs by deposition of vapor particles and aggregation of ice particles. Because of the slow updrafts we typically see continuous rainfall spread over a large distance and slowly varying over time.

Localized rain associated with either conditional instability or convective origin produce updrafts of several meters per second. There is not enough time for full growth of precipitation particles. Initial growth occurs just above the cloud base and since the time for growth is very short and rain drops grow mainly by accretion of rain drops. Heavy rainfall realized over a short period is balanced by the smaller horizontal scale of the event. When convective rainfall is observed over a large horizontal area usually it is balanced by areas that have a) either no rain b) areas having stratiform precipitation.

References

Cloud Dynamics by Robert Houze, Chapter 6

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