Weather and Climate LET’S GET READY TO TREMBLE!. Before you learn anything else, know this: Warm air rises. Cold air sinks. Air masses are large volumes.

Weather and Climate

LET’S GET READY TO TREMBLE!

Before you learn anything else, know this:

Warm air rises. Cold air sinks. Air masses are large volumes of air with

similar temperature and moisture. Cold air masses (CAM) are heavier than

warm air masses (WAM). WAM and CAM do not get along, and do

not like to be seen together. They’re funny like that.

Weather vs. Climate: It’s about time.

What is weather? Weather is what is happening in the atmosphere at a specific time. For example, right now it is cloudy, therefore the weather is cloudy. If it stops being cloudy, the weather is no longer cloudy. Too easy.

Weather vs. Climate: It’s about time.

Weather conditions normally involve measuring conditions, temperature, atmospheric pressure, windspeed, etc.

http://www.theweathernetwork.com/weather/cities/can/Pages/CANB0040.htm

Weather vs. Climate: It’s about time.

Climate is like a collection of weather. Climate refers to the average

condition of temperature, precipitation, humidity, pressure and wind in an area OVER TIME.

Weather vs. Climate: It’s about time.

So what’s the difference?Because weather is specific to time, it may

not be the same as climate. For example – the climate of New Brunswick in January is cold and dry. HOWEVER…it is not unheard of to have a January day with weather above zero degrees. By itself, this event does not affect our climate.

Condensation

Warm air rises. Cold air sinks.

Condensation occurs when warm, moist air rises, cools, and forms clouds.

But…how does that air get up there?There are three main ways we will

discuss.

Orographic Condensation

Orographic condensation occurs when warm, moist air comes into contact with higher ground.

Mount Oro

WAM cools & condenses

WAM moves toward high ground

Frontal Condensation

Frontal condensation occurs when a warm, moist air mass rises over a cold air mass. The edge of these air masses are called fronts.

Yo, man…why you frontin’?

Convectional Condensation

Convectional condensation occurs when cooler air is warmed and moistened from below.

Cool air moves over a heat source and becomes warm.

Wind

Wind

Warm air rises. Cold air sinks.WAMs and CAMs do not get along. They

do not like to mix.

Wind in a high pressure system

Wind in high pressure system

Wind in low pressure system

Wind in a high pressure system is caused when a CAM sits on top of a WAM. Because cold is heavier than warm, it pushes it down, and the warm air moves out of its way. This moving air is felt as wind.Oh

no! My hat!

Wind in a low pressure system.

Wind in a low pressure system takes place when an large air mass becomes warm and rises from the ground. Cooler air will rush in from the side to take its place. This cool air is felt as wind.

Note-taking activity

In your text, please read and make notes on page 38 (Latitude, air masses, Ocean Currents). You must identify the following:

• All 3 major air masses that affect our weather.• Both Ocean Currents• How fog is formed.

• Questions: a) In what way are ocean currents and air masses similar?

b) Which one’s effect is immediate, but longer lasting?

You will be responsible for this information on tomorrow’s quiz.

Please look up the following terms:

Anemometer Barometer Barometric pressure Beaufort wind scale

Check the glossary on this website:

www.theweathernetwork.com/inter/help/glossary/

Our 3 Major Air Masses

Continental Arctic: Air mass from Northern Canada in winter. It feels cold and dry.

Hint: think about our cold winter winds. They make your skin feel dry.

Our 3 Major Air Masses

Maritime Tropical: This is an air mass from the Caribbean. It feels warm and moist.

Hint: think about the Caribbean sea. It is warm, and humid / moist.

Our 3 Major Air Masses

Maritime Polar: Blows in from the Atlantic coast of Newfoundland. It feels cool and moist.

Hint: well…no hint here yet. Just memorize it.

Our Major Ocean Currents

Ocean currents are very similar to air masses in that they bring temperature and moisture conditions to our area.

Gulf Stream – a warm ocean current from the south. It brings warmth to the Southeastern parts of the Atlantic provinces.

Our Major Ocean Currents

The Labrador Current: Comes from the north and brings cold water to our region.

The Gulf Stream warms and moistens the air above it. The Labrador Current cools and moistens it. This is important.

Fog

Fog is formed in much the same way as clouds.

There are three main types of fog affecting our region that we will discuss.

Fog

Coastal Fog -- When the warm moist air from the Gulf Stream, meets the cool moist air from the Labrador Current, condensation occurs. Because the warm air does not need to rise to become cool, the ‘cloud’ is formed on the ground. This is FOG!

More fog…

Hill fogHill fog or upslope fog, as its name implies, is formed as mild moist air is forced to ascend a hill or mountain range. As the air moves up the windward side of the mountain it cools down, and again if the air becomes saturated then cloud is formed which, if below the top of the hills, gives fog

…so much fog

Advection fogAdvection fog is formed when very mild moist air moves over a cold ground. This can often happen in early spring in the UK when mild southwesterly winds moving across the country over snowy or icy ground. The lower layers of the air get cooled down rapidly to below the temperature at which fog forms.

…a question to ponder

Which of the three forms of condensation is most closely related to hill fog?

Snow

Snow is formed when water vapour condenses at a temperature below the freezing point.

Snow

When water vapour is warm, the particles move very quickly. As the warm air rises, cools and condenses, the particles slow down.

Snow

If the particles continue this process below the freezing point, the particles will slow to the point that they freeze and stick together. When enough of these particles stick together, they get heavy and fall as snow.

Proximity to Water – Questions to Ponder

How would you describe the weather and climate (temp and moisture) of Fredericton in the winter?

Is this different in Saint John? Does this change in the summer

months?

Proximity to Water – Questions to Ponder

Average temperature in Fredericton, NB:

Summer – (25 – 30) Winter – (-12)

This creates an average temperature range of 42 degrees Celsius!

Proximity to Water – Questions to Ponder

Average temperature in Saint John, NB:

Summer – (20 – 22)Winter – (-7)

This creates an average temperature range of 29 degrees Celsius.

Proximity to Water – Questions to Ponder

What is it about the physical location of Saint John that creates this difference in

climate?

Proximity to Water

Sunshine heats land and water at different rates. Water, and the air over it, heats and cools more slowly than land.

Proximity to Water

As a result, areas very close to large bodies of water stay cooler in summer and warmer in winter. This has a great influence over the climate of our area.