Why it rarely snows in Australia’s major cities

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It’s not because it’s too hot. There’s another factor that means while Australia is in the midst of a massive snow event, our cities are snow-free.

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A cold spell sweeping through Australia’s southeastern states turned the New South Wales town of Orange into a « winter wonderland » on June 10. A polar explosion hit many…

A cold spell sweeping through Australia’s southeastern states turned the New South Wales town of Orange into a « winter wonderland » on June 10. A polar explosion ravaged much of southeastern Australia with wintry weather, causing damaging winds, heavy rainfall, thunderstorms and flooding. Images filmed by Oscar Hunt show how Orange is covered with snow. Credit: Oscar Hunt via Storyful

Sydney’s one snowy day in 1836. Image: Climate History.Source:Supplied

There has been no shortage of snow in eastern Australia over the past week.

Half a meter fell in just a few hours at several ski resorts as the snow moved so far north that the flakes almost blew into Queensland.

Snow was seen in Orange, Oberon and also in Katoomba, the latter just an hour’s drive west of Sydney.

But again, Sydney herself was bereft of the cold stuff; just like Melbourne.

Hobart is dominated by an often snowy mountain, but the actual snow reaches the CBD below perhaps once a decade. Melbourne last saw showers in 1986, the closest Sydney got to snow was some sleet that same year.

If sunny Florida can get a little bit from time to time, why don’t the Hobart locals regularly shovel snow from their driveways?

Much of the reason for this scarcity is due to a striking difference between the Northern and Southern Hemispheres.

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Just an hour's drive from Sydney, snow fell this week at Katoomba in the Blue Mountains.  (Photo by Speed ​​KHAN/AFP)

Just an hour’s drive from Sydney, snow fell this week at Katoomba in the Blue Mountains. (Photo by Speed ​​KHAN/AFP)Source: AFP

A Tasmanian devil in the snow at Cradle Mountain.  Image: Devils@Cradle

A Tasmanian devil in the snow at Cradle Mountain. Image: [email protected]Source: News Corp Australia

Sydney’s only snowy day

It even snowed in Sydney. Not even two centuries ago. On June 28, 1836, nearly four inches of snow fell on Sydney’s Hyde Park. Even the golden sands of Bondi Beach took on a white sheen.

« A razor sharp wind from the west was blowing quite strongly at the time and all in all it was the most English winter morning… ever experienced, » the reported. Sydney Morning Herald.

It was the first time it had snowed in Sydney since colonization and it hasn’t snowed in the CBD since.

« Australia very rarely sees snow at sea level, especially compared to Europe, Asia and North America, » Sky News Weather meteorologist Rob Sharpe told news.com.au.

But that rare event reveals a misconception about snow — that is, it has to be below freezing for it to happen. On that clear day of 1836 in Sydney, the mercury only dropped to 3.3C.

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Sydney's one snowy day in 1836. Image: Climate History.

Sydney’s one snowy day in 1836. Image: Climate History.Source:Supplied

It doesn’t have to freeze to snow

In general, snow can fall easily at temperatures as warm as 2C and even as high as 5C. But at that temperature, it often falls as wet snow, a swampy mixture of rain and snow.

Sydney’s CBD fell to 5.8C on Friday morning this week, just above 5C. However, Melbourne regularly falls below that level, stopping at 1.7C on May 30.

The key is that the air temperature in clouds is at freezing point or below. Precipitation will then form into ice crystals. If the ground temperature is close to or below zero, the crystals will fall singly and the snow will be powdery. When it is slightly warmer, the crystals will melt a little and fuse with others and form large thick flakes.

But if there is no moisture in the air, no matter how cold it is, there will be no snow.

It is worth noting that hail is very different from snow. It is formed in the fury of high-altitude thunderstorms and can occur in the summer.

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Heavy snowfall in Hobart in 1986. Generally snow falls once every ten years in Hobart's chilly CBD.  But cities further north rarely see the white stuff.  Photo;  Mercury.

Heavy snowfall in Hobart in 1986. Generally snow falls once every ten years in Hobart’s chilly CBD. But cities further north rarely see the white stuff. Photo; Mercury.Source: News Limited

Australia on a snowy latitude

A lack of snow has nothing to do with being at sea level or living in coastal cities. Snow at sea level is very common around the world. However, if you are at sea level, snow generally only falls between the two poles and the latitudes of latitude 35°N and latitude 35°S.

All of Europe lies above latitude 35°N. Nevertheless, other meteorological conditions may play a role. The coastal cities of New York and Barcelona are both located at about 40° north latitude. But while Manhattan is the host of crippling snow storms, Spain is being warmed by the Gulfstream, making such an event much less likely. Although Barcelona has seen a lot of snow in 2018.

Sydney is just above this magical 35° line, meaning sea level snow is not something to be taken for granted.

Snow is much less likely to fall at sea level north of the parallel south (position ringed).  Image: Google Earth

Snow is much less likely to fall at sea level north of the parallel south (position ringed). Image: Google EarthSource:Supplied

Snow can fall on the wrong side of the 35th parallel, but it usually happens on higher ground where the temperature is lower.

Orange, in central west NSW, is more than 35° to the south, but compensates for this by being at an elevation of 900m, meaning snow most years.

All of Australia’s ski areas are both below 35th and high – the top of Thredbo is 2037 meters high. So they have two snowy elements in their favor.

Adelaide is directly at 35°, Melbourne is well below 35° and Hobart is further south.

Still, snow remains elusive.

New York regularly sees snow, in part because of its location on the edge of a continental landmass that significantly cools the winds that blow over it.  / AFP PHOTO / ANGELA WEISS

New York regularly sees snow, in part because of its location on the edge of a continental landmass that significantly cools the winds that blow over it. / AFP PHOTO / ANGELA WEISSSource: AFP

The role of land mass in snow formation

The main reason why snow is so rare in our cities, even those below the 35° line, is because of the land surrounding Australia – or lack thereof.

There is just so much more, well, earth in the north of the earth compared to the south.

« In the Northern Hemisphere, there is significant amounts of land between the poles and these mid-latitude cities like New York, meaning the air mass going into those cities is continental and can stay very cold, » said Sky’s Mr Sharpe News Weather.

« Meanwhile, the air masses coming from Antarctica to Australia travel over vast amounts of ocean, which is warmer than land at the same latitude, causing our air masses to warm up significantly by the time they arrive. »

In some cases, water can do the opposite and promote snow production. The « lake snow effect » is when cold continental air flows over lakes or smaller seas. It then absorbs warmer moisture from the lake, the droplets freeze and snow is dumped on the shore. But there are no lakes large enough to have that effect in Australia.

« Hobart and Canberra have seen the most snow of our capitals, » said Mr Sharpe.

Canberra ended up just missing out on snow at this event, as there was too much clear skies yesterday, which could allow it to warm up before the wet weather kicked in in the afternoon, » said Mr Sharpe.

Canberra is just below the 35° line and relatively high at almost 600 meters, which increases the chance of the white stuff.

The scarcity of snow in most major cities in Australia is due to many things: their sea level location, their latitude and lack of land mass.

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