weather-systems Earth Science

2 个科学问题 · 地球科学 Earth Science

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哈德里环流的下沉支为何常年锚定在南、北纬约30°的副热带?这如何解释地球主要沙漠带的分布?

Why is the descending branch of the Hadley cell anchored near 30 degrees latitude in each hemisphere, and how does this explain the layout of Earth's great desert belts?

赤道上升的空气在向极运动中因角动量守恒不断获得西风分量,到达副热带后辐射冷却并辐合下沉,下沉过程的绝热压缩使相对湿度骤降,持续抑制成云致雨。撒哈拉、阿拉伯半岛与澳大利亚内陆的荒漠正是沿这条动力性晴空带排布。基于卫星观测的多项研究表明,近几十年哈德里环流整体向极扩张,副热带干区随之向中纬度推进,加剧了地中海型气候边缘的水分亏缺。
Air rising over the equator gains strong westerly momentum as it drifts poleward under angular-momentum conservation, then cools radiatively and converges to sink near 30 degrees latitude; adiabatic compression during descent slashes relative humidity, persistently suppressing cloud formation and rainfall. The Sahara, Arabia and the Australian interior line up along this dynamically cleared belt. Multiple satellite-based analyses show the Hadley cells have expanded poleward in recent decades, pushing subtropical dry zones toward the mid-latitudes and worsening moisture deficits along Mediterranean-type climate margins.
难度 专业 · 适合 高中(15-18) CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source

出处备注：著录含书名，但缺版次 / 出版社 / 年份中的一部分，需编辑补全后才能做独立比对。

Lu & Deutscher,《哈德莱环流极向扩张:1950-1993年》,Geophysical Research Letters,2005年,第32卷

J. Lu and K. M. P. Deutscher, Poleward expansion of the Hadley circulation: 1950-1993, Geophysical Research Letters, 2005, vol. 32

#角动量守恒 #副热带干旱带

锋面附近为什么会形成大范围的云雨天气?

Why do broad bands of cloud and rain form along frontal zones?

锋面是冷暖两种性质不同的气团之间狭窄的过渡带,密度较小的暖空气被迫沿锋面爬升。上升过程中空气绝热冷却,水汽达到饱和后凝结成层状云系,并形成大范围降水。准静止锋移动缓慢,受其控制的地区常出现连续多日的阴雨天气。
A front is a narrow transition zone between air masses of contrasting temperature and density, along which lighter warm air is forced to ascend. The rising air cools adiabatically until its water vapour condenses into stratiform cloud systems that yield widespread precipitation. Where a front moves only slowly, as with a quasi-stationary front, the region beneath it can see overcast, rainy weather lasting many days.
难度 进阶 · 适合 初中(12-15) CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source

出处备注：作者 / 书名 / 版次 / 出版社 / 年份齐备，仅缺独立比对证据；已在可信度报告单列披露，不再重复核验。

朱乾根、林锦瑞、寿绍文等《天气学原理和方法》(第4版),气象出版社,2007 ; 另见: Wallace, J. M. & Hobbs, P. V. (2006). Atmospheric Science: An Introductory Survey (2nd ed.). Amsterdam: Academic Press.

Wallace, J. M. & Hobbs, P. V. (2006). Atmospheric Science: An Introductory Survey (2nd ed.). Amsterdam: Academic Press. ; see also: 朱乾根、林锦瑞、寿绍文等《天气学原理和方法》(第4版),气象出版社,2007

#天气系统 #锋面降水