Weather

Chapter 8

 “One day the Pharisees and Sadducees came to test Jesus’ claims by asking him to show them a miraculous sign from heaven. 

He replied, “You know the saying, `Red sky at night means fair weather tomorrow, red sky in the morning means foul weather all day.’

You are good at reading the weather signs in the sky, but you can’t read the obvious signs of the times!”

 Matthew 16:1-3 (NLT)

There is an introductory video here:  http://youtu.be/eZYGY29apjs

Terms to know … (good exam questions)

  • Climate is the long-term average of weather conditions and extremes in a region
  • Weather is the short-term, day-to-day condition of the atmosphere
  • Climatology is the scientific study of climate
  • Meteorology is the scientific study of the atmosphere – thus it includes study of the weather

I. Air Masses

To understand weather at a local level, global circulation patterns are important, but so are more localized weather systems associated with the specific air masses in a region.

Air masses are large, uniform bodies of air, with no major (horizontal) differences in temperature, wind and humidity.  All of the air in an air mass is more-or-less the same temperature, pressure, and relative humidity.

An air mass is a large, uniform bodies of air, with no major (horizontal) differences in temperature, wind and humidity.  All of the air in an air mass is more-or-less the same temperature, pressure, and relative humidity.  The character of an air mass is directly related to the conditions in the area where the air mass was formed.

  • An air mass that formed in moist tropical regions, will be warm and moist.
  • An air mass that formed in cold dry regions will be cold and dry.

See Figure 8.1, “Principal air masses” 4CE, p. 209 (8.2 3CE, p. 199).

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For this reason air masses are categorized (and subdivided) into 6 classes, based on where the originate (see a map of these):

  • continental arctic – cA – formed around the North Pole … very cold and very dry.  This air often forms when a high-pressure area forms over Eastern Alaska, the Yukon, Siberia or northern Canada, usually above the Arctic Circle.  Due to a near lack of winter solar radiation, abundant surface snow / ice cover and the continuous emission of radiation from the Earth’s surface the air will progressively become colder and colder.  Temperatures can reach -30 degrees C to -50 degrees C.  T Such air masses often plunge south across Canada and the USA during winter, but very rarely form during the summer because the sun warms the Arctic.
  • continental polar – cP – formed in northern regions over land … cold and dry.   These usually form farther to the south and often dominate the weather picture across central Canada and the northern USA during winter. Continental polar masses do form during the summer. These air masses are the ones responsible for bringing clear, cool — but not brutally cold — weather during the winter to most of Canada (the really FRIGID temperatures are the result of cA air masses).  In the summer, these air masses bring clear, cool weather to the Arctic.
  • maritime polar – mP – formed over northern oceans … cold and wet.  These form over the northern Atlantic and the northern Pacific oceans.  They usually bring cloudy, damp weather to Canada, including blizzards, snow or cold rain storms.   They most often influence the Pacific Northwest and the Northeast.  Since mP air is always near saturation, any lifting of the air mass (such as orographic lifting along mountain ranges) can produce widespread rain or snow. This air mass is notorious for producing fog, drizzle, cloudy weather and long lasting light to moderate rain (West Coast residents and Atlantic Canadians know all about these during the winter!).  The temperature of mP air ranges from well below freezing to low 20’s C.  Maritime polar air masses can form any time of the year and are usually not as cold as continental polar air masses.
  • continental tropical – cT – formed over southern land masses … warm and dry.  They usually form over the Desert Southwest of the USA and northern Mexico during summer. They can bring record heat to the US Plains and the Canadian Prairies and southern Ontario during summer, but they usually do not make it to the East Coast.  As they move eastward, moisture evaporates into the air, making the air mass more like a maritime tropical air mass.
  • maritime tropical – mT – formed over southern oceans … warm and wet.   Maritime tropical air masses are most common across the eastern USA and originate over the warm waters of the southern Atlantic Ocean and the Gulf of Mexico. These air masses can form year round, but they are most prevalent across the USA during summer. Maritime tropical air masses are responsible for the hot, humid days of summer across the South and the East.
  • maritime equatorial – mE … formed over equatorial oceans … very warm and very wet.  These are common along the Equator.  Lots of heat.  Lots of precipitation.

Once an air mass moves out of its source region, it is modified as it encounters surface conditions different than those found in the source region. For example, as a polar air mass moves southward, it encounters warmer land masses and consequently, is heated by the ground below. Air masses typically clash in the middle latitudes, producing some very interesting weather.

During the course of the year, our weather may be influenced by several different classes of air masses (Figure 8.1 4CE; 8.2 3CE)

On the West Coast:

  • In winter polar air dominates the Northern Hemisphere; the Arctic Front is about 38°N; the West Coast experiences cold cP (clear and cool) air masses and mP air masses (cool and wet – lots of rain and/or snow!).
  • In summer the Arctic Front retreats to about 65°N; the West Coast experiences more cT (warm and dry) and mT air masses (warm and wet).

 In the Prairies:

  • In winter polar air dominates the Northern Hemisphere; the Arctic Front is about 38°N; Alberta experiences cold cA and cP air masses.  They typically have cold, dry weather.  We also get some mP air masses (cool and wet – snow!).
  • In summer the Arctic Front retreats to about 65°N; Alberta experiences more cT (warm and dry) and a very few mT air masses (warm and wet).
  • As air masses move their characteristics change because they are influenced by the surfaces they pass over.  Thus mP and mT air masses, by the time they reach the Prairies, have usually lost most of their moisture over the west coast and the various mountain ranges to the west of us.  By the time they reach us they still have some moisture, but not much.  They are relatively dry and stable.

 In Ontario/Quebec:

  • In winter polar air dominates the Northern Hemisphere; the Arctic Front is about 38°N; Central Canada experiences cold cP (clear and cool) air masses and mP air masses (cool and wet – lots of snow!).
  • In summer the Arctic Front retreats to about 65°N; Central Canada experiences more cT (warm and dry) and mT air masses (warm and wet) — some of these can have hurricane strength!
  • Proximity to the Great Lakes means that air masses can pick up lots of added moisture meaning more snow in winter and more humidity (and thunderstorms) in summer than would be expected if the lakes were not there.

In Atlantic Canada:

  • In winter polar air dominates the Northern Hemisphere; the Arctic Front is about 38°N; Atlantic Canada experiences cold cP (clear and cool) air masses and mP air masses (cool and wet – lots of snow!).
  • In summer the Arctic Front retreats to about 65°N; Atlantic Canada experiences more cT (warm and dry) and mT air masses (warm and wet) — some of these can have hurricane strength!

 II. Atmospheric Lifting Mechanisms

  • See your text for diagrams, Figure 8.3 (4CE, p. 211) / Figure 8.5 (3CE, p. 202), “Atmospheric lifting mechanisms.”

Air masses can be “lifted” in one of four principal ways.  As the air lifts, it cools to form clouds and precipitation.  Lifting is important because it causes the uplift that leads to adiabatic cooling, condensation, and precipitation.

  1. Convergent lifting occurs in low pressure areas (like the ITCZ), air converges and rises (See Figure 8.3a (4CE) / 8.5a (3CE)). Convergent lifting refers to an atmospheric condition when there is a horizontal  inflow of air into a region. When air converges along the earth’s surface, it is forced to rise since it cannot go downward. Large scale convergence can lift a layer of air hundreds of kilometers across.
  1. Convectional lifting occurs when the ground surface heats.  This causes the air above it to heat, and the air rises by convection (See Figure 8.3b and 8.4 (4CE, p. 211-212) / Figure 8.5b and 8.6 (3CE, p. 202), “Local heating and convection”).  This is common in the Prairies and Mid West in summer:
  • Morning sunshine heats dark surfaces (soil, lakes), causing atmospheric heating, evaporation, and rising air.
  • By afternoon the moist air is still rising, and cumulus clouds often develop.
  • If the heating is intense enough, cumulonimbus clouds and thunderstorms may develop.  Before the rising air reaches the dew point temperature, it cools at the DAR – no condensation/clouds.   Once the dew point temperature is reached, it cools at the MAR  and clouds form.
  1. Orographic lifting occurs when a moving air mass encounters a physical barrier, such as a mountain range.  The air is forcibly lifted/pushed upslope.  (See Figure 8.3c (4CE) / 8.5c (3CE).  Know Figure 8.6 (4CE, p. 212) / 8.8 (3CE, p. 204), “Orographic precipitation”)
  • Initially it cools at the DAR – no condensation/clouds.
  • If it cools to the dew point it then cools at the MAR and clouds form.

The wetter slope is called the windward slope.

The drier side is the leeward slope.  On this side the descending air mass is heated by compression and water vapor evaporates.  It warms at the DAR (it is descending, so it is warming).  This descent causes temperature warming in the air due to the pressure increase with the descent. As the air warms during descent it becomes much drier, because no moisture is added to the air mass at this time.  Depending on the pressure gradient between the high pressure center and the low pressure off the coast, very strong winds with an easterly component can develop…winds sometimes as strong as 140 kmh (100 mph).

It is a very hot and dry wind, as described above. These warm, down slope winds are called Chinook winds (Alberta), Santa Ana Winds (California), or Föhn winds (central Europe).

Leeward regions are often called “rain shadow” regions.  Precipitation falls on the windward side (where the air is rising, cooling and condensing).  But on the leeward side air is descending, warming, and not condensing.  So little precipitation falls.

Consider Figure 8.7 (4CE, p. 214) / Figure 8.9 (3CE, p. 205), “Orographic patterns in …” Notice how wet the windward slopes are (the western slopes of the Olympic peninsula and Coast Mountains).  And notice how relatively dry the leeward slopes are (especially south-central Washington, in the rain shadow of the Coast Mountains).  A similar pattern happens all along the west coast, from Alaska, through B.C., to Washington and California.

  1. Frontal lifting occurs with the passage of warm and cold fronts. See Figure 8.3d (4CE) / 8.5d (3CE).

The line along which two air masses come in contact is called a front.  Where warm air is replacing cold air it is called a warm front; where cold air is replacing warm air it is called a cold front.

a.  Cold Front

See Figure 8.8a (4CE, p. 215) / Figure 8.10 (3CE, p. 206), “A typical cold front.”

Cold fronts usually have a steep slope, essentially “snow-plowing” out the warm air.  Cold fronts may cause rapid upward movement of the warm air causing thunderstorms, heavy rainfall and tornadoes.

With cold fronts, temperature changes are felt first, often followed by strong winds and heavy precipitation.

Click here for a great graphic model of a cold front.  The same site has a good

Note that the weather map symbol is a line with triangles pointing in the direction the front is moving (see the example on Page 218 (4CE) / Figure 8.12 (3CE, p. 208), “Midlatitude Cyclones/ Idealized stages…”).

b.   Warm Front

See Figure 8.9 (4CE, p. 216) / Figure 8.11 (3CE, p. 202), “A typical warm front.”

In a warm front the slope is relatively gradual; thus, cirrus clouds appear well before the front arrives … gradually clouds get thicker and thicker until low nimbostratus (rain) clouds arise.

Signs of coming changes (clouds) are seen long before temperature changes are felt on the ground.

Click here for a great graphic model of a warm front.  The same site has a good

Note that the weather map symbol is a line with semi-circles pointing in the direction the front is moving (see the example on page 218 (4CE) / Figure 8.12 (3CE), “Idealized stages…”).

c.   Occluded Front

In most weather systems, the trailing cold fronts move more quickly than the leading warm fronts.  Because cold fronts move more quickly, they often “catch” the warm front, an occlusion or occluded front occurs.

Depending on the relative temperatures of the cooler air masses, an occluded front will either resemble a warm or cold front.

Note that the weather map symbol is a line with triangles alternating with semi-circles, pointing in the direction the front is moving (see the example on page 218 (4CE) / Figure 8.12 (3CE), “Idealized stages…”).

III.     Weather Systems in Temperate (Mid-) Latitudes (Us!)

Our weather is among the least predictable in the world!  Much of our weather appears to be related to storm systems (cyclones) which form along the Arctic Front, related to the growth of Rossby Waves …

A.  Anticyclones

Anticyclones are high-pressure areas of dry, stable air and calm weather.  In summer – hot, dry weather.  In winter – cold, dry weather.  In anticyclones, air is descending and diverging.  No clouds.  No condensation.  No precipitation.

In the subtropics, anticyclone belts occur all year round at approximately 30°N and S, where air descends (subtropical highs).  Warm, dry air descends, encounters cooler air over the oceans, and a very stable condition results.  Note: major deserts in these areas!

In mid-latitudes, anticyclones periodically establish themselves for several weeks in one location, possibly due to upper wind conditions.  They cause cyclones to move around them, resulting long periods of dry weather and drought conditions.

  • When we have a hot, dry, clear period in summer, we are in an anticyclone.
  • When we have a cold, dry, clear period in winter, we are in an anticyclone.

Anticyclones are normally associated with dry, continental (cA, cP, and cT) air masses.

Anticyclones rotate clockwise in the northern hemisphere and counter clockwise in the southern hemisphere.

Does this matter?  Yes!  For example:  in winter, when an anticyclone moves into western Canada, it brings sunny, dry weather.  Because, in an anticyclone air rotates clockwise in the northern hemisphere, Lethbridge, in southern Alberta, experienced winds blowing from the south  (bringing warmer air off the US Pacific Northwest) and temperatures well above 0°C.  But in Edmonton, further north,  the winds were blowing from the north — off northern Alberta! … BRRR … temperatures well below 0°C!  The rotation of the anticyclone resulted in a temperature difference of 15°C!

B. Cyclones

Cyclones are low-pressure areas.  In these areas air is rising, cloud is forming, and precipitation usually occurs.  Cyclones rotate counter clockwise in the northern hemisphere and clockwise in the southern hemisphere.

Note:  in our latitudes, any low-pressure system can be technically called a “cyclone.”  Tropical cyclones (what we often think of when we hear the word “cyclone”) – really intense, devastating hurricanes – are different (see Tropical Cyclones, below).  For an excellent satellite image, click here.

In mid-latitudes, cyclones (or as they are sometimes called “extratropical cyclones” …. meaning they originate outside the tropics) typically track off the Pacific Ocean, north-east across the continent (propelled by westerly winds).  They bring with them strong pressure and temperature gradients (causing strong winds), and moisture.

As the cyclone progresses, air mixes, gradients decrease, moisture is lost, and eventually the storm “peters out.”

Cyclones typically are preceded by a warm front, followed by a cold front as they pass by … for an on-line idealized model, click here.

  • See the example on page 218 (4CE) / Figure 8.12 (3CE), “Idealized stages…”, and the commentary that accompanies it (“Life Cycle of a Midlatitude Cyclone”) in the text.
  • See also Figure CT 8.1.1 (4CE, p. 222) /(3CE, p. 211), “Open stage …”, which shows a typical mid-latitude cyclone.

Cyclones are normally associated with moist, maritime (mP, mT) air masses.

Does this matter?  Yes!  When Atlantic Canada experiences a dreaded “Nor-easter” — winds from the north east, the counter clockwise rotation of a cyclone or low pressure system bring cold, WET air off the North Atlantic into the Atlantic Provinces!  Lots of snow!  Wind!  And COLD!

Worth reflecting on …

In his novel, Annals of a Quiet Neighborhood, Victorian-age writer, George McDonald writes, “It was a lovely day.  The sun shone so warm that you could not help thinking of what he would be able to do before long — draw primroses and buttercups out of the Earth by force of sweet persuasive influences.  But in the shadows lay fine webs and laces of ice, so delicately lovely that one could not but be glad of the cold that made the water able to please itself by taking such graceful forms and I wondered over again for the hundredth time what could be the principal which, in the wildest, most lawless, fantastically chaotic, apparently capricious work of nature, always kept it beautiful. The beauty of the holiness must be at the heart of it somehow, I thought.  Because our God is so free from stain, so loving, so unselfish, so good, so altogether what he wants us to be, so wholly, therefore all his works declared him in beauty; his fingers can touch nothing but to mold it into nothingness; and even the play of his elements is in grace and tenderness of form.”

How do you feel about that?  Do you agree?  Feel free to discuss this quote on the course discussion site …

IV.  Violent  Weather

Environment Canada has excellent pages on both

A. Thunderstorms (click here for a graphic introduction)

Thunderstorms can be caused:

  1.      within an air mass (especially warm, moist air) – like on a hot, summer Prairie day
  2.      along a cold front – when warm moist air is shoved aloft by cold air moving in quickly
  3.      on mountain slopes when rapid orographic lifting occurs because of strong winds pushing moist air upslope quickly.

Rapidly rising moist air results in the condensation of large amounts of water vapour, massive energy release (latent energy), rapidly dropping air pressure, and strong updrafts.  These can produce huge clouds, called supercells (click here for more on supercells).

Turbulence within the atmosphere is a result.  This can be problematic for aircraft!   You don’t want to fly into a thunderstorm!  The air is moving up quickly.  And there are pockets with rapid downdrafts.  Water molecules are coalescing to form bigger and bigger droplets that eventually will fall as heavy rain.

Heavy rain normally results.  Because of the strong updrafts, raindrops will have to be very big and heavy to overcome the upward force of the air and fall.  The presence of large hail as well as strong winds classifies the storm as a severe thunderstorm.

Lightning is created by the buildup of electrical energy (tens of millions to hundreds of millions of volts) within a cumulonimbus cloud or between the cloud and the ground. Within the cloud, rapidly moving air “rubs” together, creating electrical polarities.  Lightning may be compared to the static electricity that is created when you rub two pieces of fabric together (you see sparks) – only on a much more massive scale!  80% of lightning occurs within clouds themselves, only 20% is directed toward the ground.  Lightning briefly superheats the air immediately around its path.  Within 100ths of a second the air temperature rises from normal atmospheric temperature to 15,000 – 30,000°C.

  • The most deadly lightning event in Canadian history was July 29, 1916. Lightning ignited a forest fire which burned down the towns of Cochrane and Matheson, Ontario, killing 233 people.

For a dramatic video of lightning striking a truck, check here:  lightning strikes pickup truck | CTV Edmonton News

  • For an excellent index of everything you wanted to know about lightning, click here.
  • Environment Canada also has a good page on lightning
  • For a graphic model of how lightning works, click here.
  • For current lightning information in Canada, click here.

Lightning is associated with hot weather causing rapid heating and air rising.  See Figure 8.13 (4CE, p. 224) / Figure 8.17 (3CE, p. 215), “Seasonal images …” Notice how lightning storms are common in the northern hemisphere in summer and in the southern hemisphere in winter.  Notice lightning is most intense from the equator to the tropics, as this is the region of most intense insolation.

Thunder is the noise caused by the sudden, violent expansion of this superheated air – the rapid heating and resulting expansion of the air sends shock waves moving rapidly through the atmosphere as a sonic bang.  As the shock waves pass the speed of sound, you hear a sonic boom.  This is the same sound you hear when a jet aircraft passes the speed of sound.  For a graphic model of the production of thunder, click here.  Environment

See Figure 8.12 (4CE, p. 223) / Figure 8.16 (3CE, p. 214), “Thunderstorm occurrence.”

B.  Tornadoes (Funnel Clouds)

See:     4CE, pp. 225-226; 3CE, pp. 216-219:

A man in Lincoln, Nebraska, 1943 described a tornado thus: “We looked up into what appeared to be an enormous hollow cylinder, bright inside with lightning flashes, but black as blackest night all around.  The noise was like ten million bees, plus a roar that begs description.” 

For more on what a tornado is (with graphics), click here.

Why tornadoes happen is not known definitively!  Required elements are warm, moist, unstable air, producing cumulonimbus clouds.  If there is a very steep lapse rate (air cools very rapidly) – often as a cold front pushes in – very strong updrafts and instability occur which, for some reason, occasionally spawn tornadoes.

Tornadoes are usually narrow (about 0.5 km wide) and rarely travel further than 15-20 km (but some have been up to 1.5 km wide and travel 500 km).  The funnel moves at a rate of about 50-65 km/h along the ground.  How fast the air can rotate in a tornado is not known exactly; no recorder has survived the passage of a tornado.  But speeds of over 600 km/h are believed to occur.

Wikipedia has a good article on tornadoes.

Check out satellite images, including java animation of the Pine Lake, AB (2000) tornado.

Tornadoes are measured on the Fujita Scale (Click for pictures) … F0 to F5.  See Table 8.1 (4CE, p. 226) / Table 8.1 (3CE, p. 218), “The Fujita Scale.” The Edmonton tornado of 1987 was an F4.

From 1916 to the present an average of 230 people per year are killed by tornadoes in the U.S.   For the United States’ worst tornadoes, click here.

Canada’s Worst Tornadoes

Central North America is “Tornado Alley,” with frequency being highest in the Gulf in February/March, and July/August in Canada.  Typically they happen when cool moist mP air lifts very warm moist mT air.

Destruction happens two ways –

  • extremely high winds
  • severe pressure changes (very quickly dropping from normal, 1013 mb to as low as 600 mb).

This combination often causes buildings to be lifted off their foundations or to literally explode (higher pressure inside than outside).  In some cases straws have been found embedded in railway ties!

  • The movie Twister provides a reasonably accurate portrayal of tornadoes and the damage they can cause.
  • Everything you want to know about tornadoes …  click here.
C. Tropical Cyclones (also known as Hurricanes or Typhoons)

In much of the trade wind belt the weather is very consistent – small convection clouds, occasional afternoon showers (heavier, more frequent in summer because of higher temperatures and uplift).  Mild storms, associated with easterly waves also occur.  The exceptions are known as Tropical Cyclones. The terms hurricanes (used in the Atlantic Ocean) and typhoons (used in the Pacific Ocean) are also used to describe tropical cyclones.  They are synonyms.

Whereas mid-latitude cyclones are large, revolve slowly and are rather ponderous, tropical cylones are small, revolve very quickly and move swiftly.

  • Tropical cyclones are classified as storms with winds over 120 km/h.
  • They form over tropical seas (27°C +), from about 5°N and S to 20°N and S (but not at the Equator).  For a map of source regions, click here.

Exactly how they form is unknown – it appears that localized strong updrafts can produce small storms or squalls that then intensify as they travel across the ocean.  Rapid evaporation, uplift and condensation causes great quantities of latent heat to be released, fueling the storm with much energy.  The Coriolis force causes the spiral effect that, although weak, causes the air to begin to rotate.

In the Northern Hemisphere hurricanes occur May-November (the warmest months)

Hurricanes consist of a spiral of thick, black clouds packing torrential rains, centered around a calm, clear, low pressure “eye” of descending air.  Around the eye winds often exceed 250 km/h.  Winds decrease in strength away from the eye but gale force winds (60 km/h +) often extend more than 300 km away from the center of the storm.

Once hurricanes hit land they weaken because of friction with the ground and because their fuel source (warm, ocean water) disappears.  However as the winds drop, precipitation often continues because so much moisture was evaporated and then condensed in the clouds.

Hurricanes often follow predictable tracks.  In the Atlantic Ocean, for instance, following the east coast of North America and in the Pacific, from the west coast of central America into the Pacific Ocean.

Hurricanes also often create large waves.  In Bangladesh, Nov.12, 1970, between 300,000-500,000(!!!) people were killed by a hurricane, mostly by storm surge waves (up to 12 m high).  This was one of the greatest natural disasters of the twentieth century.  (Have you ever heard of it?  Interesting how disasters in some parts of the world get more attention than others, isn’t it?  Why is that?)

The Canadian Hurricane Centre has an excellent introduction to everything hurricane-ish, especially as it relates to Canada’s east coast.

  • September 2003, Hurricane Juan was particularly vicious, resulting large-scale destruction.  Hurricane Juan tore down power lines, flooded waterfront properties, sank dozens of yachts, heaved sidewalks and damaged stately downtown homes in Halifax and Charlottetown.  At its peak, Juan left more than 300,000 homes without power in Nova Scotia and Prince Edward Island.  There were sustained winds at 158 km/h gusting over 185 km/h. Winds generated a storm surge of over 1.5 m, and raised the water level in Halifax harbour to a record 2.9 metres.  Maximum wave heights outside the harbour were measured at nearly 20 metres. Mercifully, rainfall amounts from Juan were not heavy at 25 to 40 mm.
  • Hurricane Hazel, 1954, was particularly devastating to Toronto and southern Ontario.  Hazel dumped an estimated 300 million tonnes of rain on Toronto, causing lost streets, washed out bridges and untold personal tragedy. In all, 83 people died — some bodies washing up on the shores of Lake Ontario in New York State days later.

For a list of major hurricanes affecting Canada, click here.

Recent global hurricanes/typhoons of note include:

One of the consequences of climate change appears to be an increase in the frequency and severity of hurricanes, incurring greater costs and new building guidelines:

 D. Blizzards

Blizzards are severe winter storms characterized by the following:

  • snow or blowing snow with winds of 40 km/hr or more,
  • visibility reduced to less than one km in snow and/or blowing snow,
  • windchill of -25°C or colder.

All of the above conditions must last for four hours or more to be officially classified as a blizzard.

Canada has no recognized classification system for blizzards.  The United States has developed the The Northeast Snowfall Impact Scale (NESIS) — a four point scale that rates blizzards ranging from Notable (the weakest designation) to Significant, Major, Crippling, and Extreme. They created this measuring system due to the effects these storms have on the economy and transportation..

Blizzards can occur in any Canadian province or territory.  Alberta and the Atlantic provinces receive the most blizzards in Canada.

The Iran Blizzard of February 1972 is the deadliest blizzard in history (every hear of it?  It’s time you did!).  It resulted in the deaths of approximately 4,000 people.  In a week southern Iran received almost 8 m  of snow, completely burying several villages and killing all the residents.

Other notable blizzards include:

E. Ice Storms

An ice storm is a  type of winter storm characterized by freezing rain.

The worst ice storm in Canadian history, the massive Ice Storm of January 1998 affected a huge area from eastern Ontario, through Quebec and New Brunswick to Nova Scotia.  It caused massive damage to trees and electrical infrastructure all over the area, leading to widespread power outages. Millions were left in the dark for periods varying from days to weeks, leading to more than 30 fatalities, a shut down of activities in large cities like Montreal and Ottawa and an unprecedented reconstruction effort of the power grid.

The 2013 Central and Eastern Canada ice storm  left over 700,000 people in Ontario, Quebec, New Brunswick, and Nova Scotia without power for up to 12 days.

A list of major ice storms is here:  List of ice storms – Wikipedia, the free encyclopedia

To reflect on …

Astronomer Jennifer Wiseman, director of NASA’s Hubble Space Telescope programme,  thinks that you can’t find out whether there’s a God from looking at the universe, but here she describes what she sees – as a Christian – in the discoveries of astronomy.

Check out the video “Science affirms my faith” with Natalie, a plant geneticist

To review …

Check out the resources at www.masteringgeography.com

This page is the intellectual property of the author, Bruce Martin, and is copyrighted © 2019 by Bruce Martin.  This page may be copied or printed only for educational purposes by students registered in courses taught by Dr. Bruce Martin.  Any other use constitutes a criminal offence.

Scripture quotations marked (NLT) are taken from the Holy Bible, New Living Translation, copyright © 1996. Used by permission of Tyndale House Publishers, Inc., Wheaton, Illinois 60189. All rights reserved