INDEPTH: FORCES OF NATURE|
Weather: Be prepared
Gary Katz, CBC News Online | July 15, 2003
We live in air like goldfish live in water. We call it the atmosphere. If there's no air under the sea, up in space, trapped in a collapsed mineshaft we can get into big trouble. But we're also in big trouble if the air around us gets mean. We like a breeze and we can stand a wind, but a hurricane is one of the most destructive forces on the planet.
Since the air that surrounds the Earth like a white around a yolk also contains the moisture that produces rain, air conditions also mean water conditions. There again, the range between a gentle drizzle and a monsoon is more than just quantity, at least in terms of its effect on anything that lives in its path.
The third partner in weather is heat since air and moisture are dramatically affected by it. As air heats it achieves buoyancy and absorbency; as it cools it loses both. Though the range of temperatures on the Earth's surface is only about two per cent of the temperature on the sun, both the top and bottom end can be fatal to life.
The three air, water, heat make "weather," what the atmosphere is doing at any given time in any identifiable place.
- Surface of our sun is approx. 6,000° C.
- Earth record temperatures range about 130° from highest to lowest.
- The records are: 58 C at Tripoli, Libya, and -70 C at Verkhoyansk, Siberia.
- Range on Earth is about two per cent of the temperature on the sun.
The Weather Dance
You might say weather starts at the equator, the place on the planet that receives the most heat from the sun. Heated air rises above the equator (creating a lowpressure belt around the planet's middle) and heads for the poles where it cools, drops downward, and returns to the equator like a world-class draft along the floor.
North and south of the equatorial lowpressure band, approximately 30 degrees or about 3,000 kilometres, the highest hot air cools and falls creating highpressure belts around the planet. There are also winds that radiate from the poles where the air stream cools and reverses its journey. These polar winds and the 30-degree band meet and form a 60-degree band. These are the stripes of churning air that, in combination with the spinning world, cover the globe with winds and weather.
But equatorial sun isn't the only source of weatherproducing heat. The sun covers the entire planet in varying degrees of warmth, depending on season and surface characteristics. The heat relationship between large landmasses and nearby bodies of water can set up its own wind system. Ocean currents affect the air above them and the Gulf Stream, for instance, profoundly influences weather up Canada's East Coast as it carries its tropical heat northward at the meandering rate of about six kilometres per hour.
And humans produce heat, too, in ways the natural order couldn't have foreseen.
The effects of a city on the environment can be enormous as human activity and technology throw up heat and clouds of pollution. Urban centres become hot spots compared to the area outside the city limits and, though the difference in temperature may average one to two degrees C annually, that number may be significantly higher sometimes. On a clear, windless summer evening the difference between urban and suburban can be as large as 10 degrees in Hamilton, and 12 degrees in Winnipeg, Edmonton or Montreal.
Our best defence against dangerous weather is predictability. We want to predict when the next threat will occur and we want to be able to predict what the effects of the assault are likely to be. There are few situations in which it is truer that "forewarned is forearmed" than in dealing with atmospheric attack. In human terms, it's less important that weather be pleasant than that it be predictable. There's almost nowhere on the planet where prepared people can't live. The danger is when conditions go beyond the norms we've prepared for.
We begin our defence against weather by knowing the climate. Climate is the range of expectable weather in an area over time based on observations about the past. The part of the living world with no technology insects, birds, animals, plants settle and live where the climate is congenial to their needs. Humans can stretch the limits a bit if we know what to expect.
We prepare for normal climate and, if we can, for a bit of an extreme just to be on the safe side. When the exceptional occurs we need to know as soon as possible because our normal preparations may not be enough. And it doesn't matter how prepared we are if, after we've laid our best defences, the climate changes.
Today's weather technology studies and describes climate in terms of a large number of factors. Environment Canada has rated the climates of Canadian cities according to 17 different weather stressors including extremes of hot or cold; wetness, dryness and windiness; periods of continuing darkness or daylight; prolonged or intense precipitation; fog and restricted visibility; lightning and thunderstorms; blowing snow and freezing precipitation and bad air.
This scientific approach to understanding and recording weather is far advanced from the first scientific climatemeasuring device the calendar. It was a major leap for someone to realize that weather was cyclical, and there are few things more worth measuring than the amount of time you've got between spring planting and autumn frost. Now our cycle of observation is longer than a single year. You'd think we were well on the way to being prepared for anything, weatherwise.
But how long is a cycle when it comes to climate? If you studied the skies for 50 years, you might never know about Halley's comet. If you watched for a hundred, you'd know about it but you might not know when to expect it again, if ever. After 500 years of record keeping, you could predict with confidence its next appearance. But knowing an event's probable cycle may not be enough.
If we know that a devastating weather event may occur only infrequently there must be policy questions about how much resources to put into preparation for it. When Premier Duff Roblin of Manitoba proposed spending millions of dollars in the 1960s to protect the city of Winnipeg against relatively infrequent major flooding, the project was derided by many as "Duff's Ditch." Recent history casts the decision in a considerably more positive light. But what if the devastating flooding occurred only every hundred years? It has been estimated that a hurricane with the destructive force of Mitch may be a onceintwocenturies event. Having that information raises questions not answers.
The short list of things that are affected by weather is:
Even if the closest you get to a wheat field is the bakery department in Safeway, you're deeply affected by agriculture both as a food source and as an economic engine. And agriculture lives or dies on weather. That's only one of the more obvious relationships. Insect populations, both as food chain dainties and as disease carriers, ebb and flow with the weather. Floods, fisheries, forest fires, birth and suicide rates. The weather has a profound effect on all of them.
Our best means of thriving on our home turf, like our best defence against natural disaster, is to expect what the weather will offer, to know and understand the climate. That understanding governs what we plant, how we build, what we trade, the very structure and nature of our society.
Given the amount of energy that goes into accommodating the weather, given that entire civilizations are based on an understanding of climate, it's no small thing if the climate changes. If it changes naturally, as in the case of the ocean current El Nino, we must try to place the phenomenon into our understanding of the cycles that affect the climate. Next time we'll expect it and know better.
If climate changes unnaturally, as in the case of global warming, we must try to understand the effect of this new feature of the world's weather as quickly as possible, either to reverse it or to accommodate it. A few degrees more or less heat, a few days change in when the frost comes, and the foundation of an entire population can be put at risk. The extra water frozen or melted at the poles can lower or raise water levels throughout the world, changing the climatic conditions we count on for survival.
It may seem, in the midst of a Canadian January, that several degrees more warmth than usual is just a little postChristmas gift. Until a "freak" ice storm leaves a few million people freezing in the dark.
Environment Canada has made an index of weather effects in cities across the country. The index has a range from 1 (best) to 100. We have no 1s but at least we have no 100s. We had a 99, Isachsen weather station in the NWT, but it was closed down in 1978.
The index measures 17 yearround weather stressors. The list includes extremes of temperature and moisture, windiness, air quality; continuous darkness or daylight, prolonged or intense precipitation, fog and restricted visibility; thunder and lightning storms, blowing snow and freezing precipitation and more.
The index takes into account four major factors most directly related to environmental stress: winter and summer discomfort, psychological state, safety or hazardousness of a place, and limitations on outdoor mobility. Essentially, the index considers comfort primary since that affects everything from what we wear to whether we go outside voluntarily to how we feel emotionally and physically.
Source: Canadian Encyclopedia
|Victoria, B.C. ||13 |
|Vancouver, B.C. ||18 |
|Calgary, Alta. ||34 |
|Toronto, Ont. ||35 |
|Edmonton, Alta. ||37 |
|Windsor, Ont. ||37 |
|London, Ont. ||41 |
|Saskatoon, Sask. ||42 |
|Ottawa, Ont. ||43 |
|Halifax, N.S. ||44 |
|Montreal, Que. ||46 |
|Sudbury, Ont. ||46 |
|Regina, Sask. ||47 |
|Charlottetown, P.E.I. ||48 |
|Saint John, N.B. ||48 |
|Winnipeg, Man. ||51 |
|Quebec City, Que. ||52 |
|ChicoutimiJonquière, Que ||54 |
|St. John's, Nfld. ||56|
Obviously, this list only measures one group of influences on a city and isn't intended to rate quality of life. There are more reasons for choosing a place to live than the weather. But it's not far down the list.