閃電識轉彎

 31/5/2023

前天文台助理台長梁榮武表示已看過網片，坦言：「我都係第一次見到。」他指即使大廈有安裝避雷裝置，亦無可能做到百分百保障，凡事總有例外(官方答案）。他解釋閃電並非行直線，而是行不規則的「之字型」，所以雷電未必次次都會擊中避雷針，今次就是一個例子。

梁榮武又指，大廈頂層或天台安裝的避雷針，一般是由粗銅線製成的金屬棒，可以將附近的雷電吸引過來，直接引流落地下，保護建築物不受雷擊。他形容避雷針猶如一把無形的雨傘（球體？），理論上在雨傘範圍內是不受雷電的衝擊，尤其對最高十層八層樓，而中層或低層則可能脫離保護傘的保護。至於避雷針保護範圍究竟有多廣，則要視乎避雷針設計。

梁榮武表示，現代的高樓大廈建築物料及結構良好，雷電擊中單位的牆身，應不會對屋內住客造成傷害（沒有proof, see myth debunked below）；即使雷電擊中汽車，根據「法拉第籠」Faraday cage 效應，車內的乘客亦不會有事。但他補充指，閃電本身是一個極強的電流，產生的電磁波，會對室內的電器或電線帶來感應電流（induced current），如果感應電流太強，或會造成電器故障或損毀。

工程師學會電機分部發言人何永業:

電流會服從物理定律尋找最低電阻的路徑

中文大學物理系高級講師湯兆昇:

雷電劈中大廈中層的機會雖然較低，但涉及隨機因素故較難估計和預先掌握

香港建築師學會會長陳澤斌回覆本報指，在大廈最頂點安裝避雷針和設置避雷帶都是最常見做法(沒能解釋今次 side strike)

Here we need to talk about probability, and how to reduce risks.

用Rolling sphere protection come method:滾球法 解釋更到位

10 Myths debunked 

Is it completely safe to stay indoors?

Building structure with four walls and a roof is better than a vehicle for riding out a storm because of the physical protection that it provides. That doesn't mean, however, that you're completely safe from lighting once your foot crosses the doorway. In fact, you should step as far away from the door – and any windows – as possible. These and other openings provide a space for lightning to invade the structure

It's also a very good idea to steer clear of anything inside the building that conducts electricity, such as landline phones, and electrical appliances. Because surge protectors don't protect against lightning strikes, try to unplug devices like televisions, computers and anything else attached to a cord. Even indoor plumbing and metal window and door frames are lightning conductors that can raise safety hazards during a storm. So if dark clouds and thunderclaps have forced you to cut that jog around the neighborhood short, you're just going to have to wait until it's over before you hit the shower.

Reference

Yahoo news 

am730

CNA

Weather gov 

Calculation know how 

BS EN/IEC 62305 ( 香港有否採納implement?)

Paschen law 

Lightning simulator