06 Aug 2019

Understanding Winter Before It Hits


During the 17th Century, temperatures dropped so low that the Earth experienced a mini-Ice Age. It was so cold in London that the River Thames froze over!

This strange chilly weather was caused by an absence of sunspots - just one of the freak conditions that can lead to suddenly plummeting temperatures. Let’s take a look at the science behind why winter happens, and what can make it unpredictable. 

What is Winter?

We all know the Earth takes 365 days (a year) to travel around the sun. Due to the way our planet is tilted on its axis at 23.5°, each hemisphere spends part of this journey tilted towards the sun, resulting in warmer temperatures, and part of the year tilted away, resulting in colder temperatures.

It may surprise some to know that in the northern hemisphere, during the winter months, the Earth is actually closer to the sun than it is during the summer months. The Earth’s orbit is not a perfect circle, but rather an elliptical pattern. So it is not the proximity to the sun that causes our seasons, but the axial tilt as mentioned above.

During the summer months, the sun’s rays hit that part of the Earth at a steeper, more direct angle. Light doesn’t spread out much, so more energy hits the Earth at each spot it encounters. And with slightly longer days, there are more hours for the land to absorb heat.

During the non Spring or Summer months, the sun’s rays hit that part of the Earth at a shallow, less direct angle, spreading radiant energy more thinly. And the longer nights leave less time for things to warm up. This is winter.

The farther you are from the equator, the more dramatically these changes affect you over the course of the year. It also means there’s much more scope for extreme shifts and unpredictable weather events, especially when combined with the other factors we’ll look at in a moment.

Jet Streams and Pressure Systems

One weather phenomenon that’s exaggerated by winter weather further north and south is that of jet streams. 

These are narrow bands of strong wind that follow the boundaries between hot and cold air. They blow from west to east, following the rotation of the Earth, but gravitate towards the north and south poles. What’s more, the further they get from the equator, the faster these winds blow eastwards. 

To complicate matters, though, jet streams move further towards the poles in summer and closer to the equator in winter, but their paths are also shaped by encounters with hot and cold air, and high and low pressure systems. At times they split in two, forming different paths, and at times they merge together.

Since they trace the boundaries between hot and cold air, which are most pronounced during winter, jet streams are most prominent in places that experience the harshest effects of winter. In other words, the further north and south you go. That makes these areas particularly prone to erratic winter weather, which can be very hard to plan for.

What About Sunspots?

While seasonal patterns are easily anticipated and the paths of jet streams can be at least partly predicted year on year, sunspots are a different story entirely.

Sunspots are dark patches that form on the photosphere, on the surface of the sun. These spots look dark because they’re about 2,000 degrees Kelvin colder than the rest of the photosphere, but when energy from them is released, they cause huge storms and solar flares that give out massive bursts of heat. 

If there aren’t any sunspots, it means that the sun is spitting out a little less energy than usual, which affects the temperature here on Earth. Meanwhile, because the Earth is tilted on its axis, during winter the sun’s rays hit the surface at a shallow angle, spreading the same energy across a wider space, while the long nights leave little time to warm up again. 

With the double whammy of less energy to start with and this energy spread thinly, this can mean very cold winters indeed.

This year, NASA scientists have detected the same thing happening again. They expect the sun to reach its “solar minimum” in the next two years, which means things could get dramatically colder for a little while.

That could have serious consequences for your jobsite, especially if your construction team is exposed to the elements. No matter how warmly you wrap up, there comes a point when conditions are simply too harsh to work in.

What Does This Mean for You?

It’s not just your personnel that struggle with the cold. Plummeting temperatures can slow work to a crawl and cause some equipment to break down. Concrete cures pours are delayed. Frozen ground can be impossible to work with. A snowstorm can wreak havoc on your schedule, knock out your key utilities or make it impossible to get in and out of the site. 

All of these problems can lead to a similar outcome: a slowdown or complete stoppage of work until you can get up and running again.

The key is not to wait until that happens. Audit your jobsite now to identify every element that could be affected by an unusually cold winter, and establish a temporary power and heating strategy to handle it. Bringing in generators and electronic or hydronic heaters can allow you to stay ahead of schedule and under budget.

Proper contingency planning, developed in tandem with a temporary utility company you trust, gives you the peace of mind you need to know that the backup works and the right equipment is available in your area, the moment you need it. That way, you’ll get construction up and running in no time, whatever the weather brings. Ignore the warning signs and you’ll be on thin ice!