HAMNET Report 21st July 2024

A magnitude 7.3 earthquake struck Chile close to the Bolivian border on Friday morning the 19th July at 03h50 Central African time, exposing a population of about 140000 to Magnitude 7 shaking. By Friday evening, no reports of casualties had trickled through yet

You will have noted that two South African provinces were declared disaster areas this week, and for opposite reasons. KwaZulu Natal had parts of the province given disaster status as a result of extreme heat and uncontrollable fires, which claimed some lives amongst firefighters and the public, and the weather hasn’t abated there yet, so disaster management teams and firefighters remain on alert.

And the Western Cape was declared a disaster area as a result of very high rainfall, and damaging winds and storm surges, after a succession of cold fronts battered the Cape. As I mentioned last week, the informal settlements scattered along river banks and in low-lying areas were generally washed away, and this week, starter kits of materials with which to rebuild houses were issued out to many destitute residents.

And rain-wise, this week was no better. I live in a central Peninsular area, where rainfall is usually milder than the classical wet areas, like Newlands and Rondebosch, but even I broke my previous records for the most rain in one calendar month, since I started keeping records in 2001. Since Wednesday the 3rd of July, I have recorded 271 mm of rain, soundly beating my previous record of 247 in August 2013. And we still have another 10 days of July to get through. In the last six days, I have recorded 144mm, but I’m sure places like Newlands, the Tygerberg and the catchment areas of the main dams serving the Western Cape will have experienced 2-3 times as much. I believed those same dam’s increased their levels by 20 percentage points this week alone.

I give thanks that our rain doesn’t all arrive in one day, like KZN experiences, and bridge wash-aways and loss of life is not as marked. Meanwhile, the inland high ground is threatened with snowfalls, particularly over the Ceres, Cedarberg and Koue Bokkeveld area, as well as the Sani Pass and Giant’s Castle portion of the Drakensberg, and the south-eastern tip of Lesotho. Winter ain’t over yet!

BBC.com pertinently asks the question: Do tornadoes or hailstones do more damage?

The world is devastated by 1000’s of tornadoes each year. Yet, in 2023, heat claimed more than double the fatalities caused by tornadoes, surprisingly, and hail can account for 60-80% of insured losses from thunderstorms – more than tornadoes do.

To those who have only experienced mild hail, the icy sprinkles may seem harmless by comparison. But hail can unleash a torrent of chaos. In June, a plane travelling from Spain to Austria had its nose cone ripped away and its cockpit windows smashed after flying into a hail storm. In 2018, softball-sized ice pummelled a Colorado zoo, killing two birds and injuring 14 people. And, although rare, hail can be fatal to humans too, with eight deaths recorded in the last 70 years.

Tornadoes get a lot of publicity, but hailstorms can span kilometres and last hours, and do far more general damage. Their reach and frequency means hail storms are a particular challenge for the insurance industry. According to Ian Giammanco, a meteorologist and managing director of standards and analytics at the Insurance Institute for Business and Home Safety (IBHS), only about 10% of all hail-producing thunderstorms cause damage – but those that do, wreak havoc, with hail accounting for “more than $10bn in the Americas in insured losses every year since 2008”.

At just 2.5cm hail can start to damage vegetation, Giammanco says. By 3.8cm, it can dent cars and older, shingle roofs. By 5cm it cracks car windshields and damages most building materials typically used in US construction. Bigger than 5cm, hail has the potential to crack plywood decking and at 10cm it can come through your roof.

Climate change is strengthening storm updrafts, according to an upcoming paper by Prof Vittorio Gensini and colleagues. Updrafts work like a hairdryer pointing upwards, Gensini explains; the stronger the thrust of air, the larger the ice-ball you could balance at its top. Therefore as the updrafts become stronger, bigger hailstones can be created. However, the warming climate is also causing more, smaller hailstones to melt before they hit the ground, he counters. 

Unfortunately, the two threats – hail and tornadoes – commonly are found close together. The strongest, rotating and tornado-forming thunderstorms – known as supercells – are produced by the same atmospheric conditions that are also likely to create hail. 

So in essence, you get whacked on the roundabouts as well as on the swings!

Very exciting this week was the monitoring of the sunspot number, which on Thursday, Friday and Saturday reached a staggering figure of 275 (gathered together in groups of course), only 10 sunspots less than the record of 285 measured during the peak of solar cycle 19, in March 1958, the best solar cycle ham radio has ever experienced. I personally listened to one of my Elmers working Hawaii (KH6) on 2watts USB on 20 metres from ZS5-land at that time! Let’s hope it happens this cycle too. Folks, turn on your radios and listen around!

In a short paragraph written for Hackaday by Jenny List, she wonders whether hackers are the future of amateur radio.

She says “If amateur radio has a problem, it’s that shaking off an image of being the exclusive preserve of old men with shiny radios talking about old times, remains a challenge. Especially, considering that so many amateurs are old men who like to talk a lot about old times. It’s difficult to attract new radio amateurs in the age of the Internet, so some in the hobby are trying new avenues. Dan, KB6NU went to the recent HOPE conference to evangelise amateur radio, and came away having had some success. We agree with him, hackers can be the future of amateur radio.

“In the slides from his talk, he goes through all the crossovers between the two communities from Arduinos to GNU Radio. We don’t need persuading; in fact we’d have added UHF and microwave RF circuitry and pushing the limits of the atmosphere with digital modes such as WSPR to the list as our personal favourites. It seems he found willing converts, and it’s certainly a theme we’ve featured before here at Hackaday. After all, unless it retains its interest, amateur radio could just die away.”

I’m not sure that amateur radio will just die away, but I do agree that the hacker mentality will certainly add to the enterprising spirit needed to keep amateur radio interesting to the new ham. What do you think?

This is Dave Reece ZS1DFR reporting from a soggy Cape Town for HAMNET in South Africa.