CHAPTER 3 :THE CHANGING WEATHER What Is a Snowstorm? Two factors are essential in the creation of a snowstorm: snow and wind Snow forms when water vapour.

CHAPTER 3 :THE CHANGING WEATHER

What Is a Snowstorm?Two factors are essential in the creation of a snowstorm: snow

and wind

Snow forms when water vapour condenses at a temperature below the freezing point. As it condenses it forms ice crystals that join together and make snowflakes.

CHAPTER 3THE CHANGING WEATHER

Snow pg. 34Condensation: the process by which moisture in the air changes to liquid or solid form. Examples are rain, clouds, and snowflakes.

Condensation occurs when moist air rises and cools. It then forms clouds.

CHAPTER 3 : THE CHANGING WEATHER

Snow Pg. 34Air may rise for several reasons: it may be blown

over high ground, it may be warmed from below and rise, or it may be forced upward by a colder and denser air mass.

You may think that areas that get the greatest snowfalls would see schools close most often however average snowfall is not a reliable predictor of storms


Snow pg. 34The second ingredient-wind-is essential to a

storm.

Snow drifting down in soft white flakes generally does not pose much of a danger to traffic.

However, propel that snow with fast-moving air and it may become a blizzard that is hazardous to most forms of transportation

CHAPTER 3: THE CHANGING WEATHERWind pg. 36

Wind is air that is moving from an area of high pressure to an area of low pressure.

High Pressure: an atmospheric condition caused by the sinking of cool air

Low Pressure: an atmospheric condition caused by rising of warm air

CHAPTER 3 - THE CHANGING WEATHERWind pg. 36

Hot air rises cool air sinks

A warm surface will heat the air above it causing it to rise. This creates an area of low pressure beneath the rising air.

An area of high pressure occurs when the cool air sinks towards the earth’s surface and pushes the air underneath it away.

You're well familiar with our "H" and "L" designations on weather maps for areas of high and low pressure, but what do they mean in regards to what weather's coming?

High pressure situations are generally associated with fair, sunny weather. As high pressure is an area of sinking air, and air tends to dry out as it sinks, leaving sunny skies.

Low pressure areas are generally cloudy/rainy areas -- where strong areas of low pressure bring our stormiest weather. That's because it's an area of rising air, and as air rises, it condenses into clouds and rain. Air moves from higher pressure to lower pressure, so if you have a high and a low nearby, it can be windy as air rushes between the two

CHAPTER 3THE CHANGING

WEATHER

http://www.ctv.ca/weather/



Air at the poles sinks because it is cold. Air at the equator rises because it is warm.

So how does that affect weather in the Atlantic Region.

These air masses do not stay in one place because of the earth’s rotation.

CHAPTER 3: THE CHANGING WEATHER

Climate: average conditions of temperature, precipitation, humidity, air pressure, and wind

Precipitation: rain, snow, and any other forms of water particles that fall from the atmosphere

Weather: conditions of the atmosphere over a short period

CHAPTER 3: THE CHANGING WEATHER

4 Factors That Influence the Climate of Atlantic Canada:

1)Latitude2)Air masses3)Ocean currents4)Proximity to water

All parts of the world receive the same total number of daylight hours over a year.

The earth’s surface is curved so sunshine is more intense in lower latitudes

How does this influence climate? Cape Sable, Nova How does this influence climate? Cape Sable, Nova Scotia at 43*N receives more intense sun than Scotia at 43*N receives more intense sun than Killinek, Labrador at 60*NKillinek, Labrador at 60*N


Air Masses are… large volumes of air with similar temperature

and moisture conditions throughout

Air masses take on the temperature and humidity characteristics of the areas in which they originate

For example, when Maritime Tropical air comes in from the Caribbean it feels warm and moist

Air masses, like wind, move because of changing pressure


The leading edge of an air mass is known as a front.

Front: The leading edge of an air mass, bringing characteristics of the air

mass; they often result in a change in temperature

Most precipitation in the Atlantic Region comes about when cold dry air from the north meets warm moist air from the south.


Ocean Currents: the movement of water in the world’s oceans

Water in the oceans is constantly in motion; tides move the water up and down-ocean currents move water from place to place.

The two currents that affect the Atlantic Region most are the Gulf Stream and the Labrador Current


Gulf Stream: an Atlantic Ocean current from the south; it brings warmth to the southwestern waters of the Atlantic provinces

Labrador Current: an ocean current from the north; it brings cold waters to much of the Atlantic coast


When the two currents meet fog is often the Result. The warm moist air of the Gulf Stream Is cooled and condenses.

The water vapor droplets are not large enough to fall as rain so they remain suspended in the slowly moving air.


4/ Proximity to the Ocean

Sunshine heats land and water at different rates:

Water, and the air over it, heats up and cools down more slowly than land.

As a result areas close to large bodies of water stay cooler in the summer and warmer in the winter than areas that are inland

This affects the climate of many Atlantic towns close to the ocean.


CHAPTER 3 :THE CHANGING WEATHER What Is a Snowstorm? Two factors are essential in the creation of a snowstorm: snow and wind Snow forms when water vapour.

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