1. Weather: Chapter 14 Sec 14.1 Meteorology Meteorologist
The study of atmospheres and weather
Meteorologist
Someone who studies atmospheres and weather.

2. Sec 14.2:Weather Systems Weather systems
Set of temperatures, wind pressures, moisture conditions for a region that moves as a unit for a period of days.
In N. America they are pushed west to east by mid-latitude westerlies.

3. Four main air masses of N. America
Large body of air in which the temperature and moisture content at a specific altitude are fairly uniform.
Air mass stays stationary for a period of time
Can be small 100Km or large 1000Km
Four main air masses of N. America
Maritime polar
Continental polar
Maritime tropical
Continental tropical

5. Continental air masses
Maritime air masses
Formed over water
Are moist, bring rain
Continental air masses
Formed over land
Are dry
Polar
Formed at poles
Are cold
Tropical
Formed around equator
Are warm

6. Fronts: Warm Front: Leading edge of a moving air mass.
Warm air moves into/over a cold air mass and carries moisture .
Creates nimbostratus clouds.
Direction of air mass movement is indicated by the direction of the “bumps”

7. Cold front Cold air moves into/under a warm air mass.
Creates cumulus clouds, heavy precipitation.

9. Stationary Front
Boundary between warm air mass and cold air mass remains still for some time.
Appears on weather maps as:

10. Occluded front A cut-off or closed front.
As a storm grows,one front rotates around the storm and catches another. This forms an occluded front, which is the boundary that separates the new air mass (to the west) from the older air mass already in place.

11. Fronts and Systems:

14. Regional Weather
General weather conditions of a region such as temperature, humidity, precipitation, and winds

15. Convection Current
When a temperature difference occurs in a fluid (water or atmosphere). Hot fluid rises and cold fluids sink which create a current or movement in the fluid

16. Sec 14.4 Regional Weather 1. Thermals
The uneven heating of the Earth’s surface from radiation
Are created when;
sun heats land,
energy absorbed by the land heats the air
air warms, expands and rises.

18. Sea Breeze: day time
A cool breeze flowing over the land from the sea that occurs during the day when land warms because a convection current is created when:
Warm air over land rises
Sea breeze moves inland replacing the air
Upper cool air cools and sinks

19. Land breeze
A cool breeze blowing towards the sea at night because land cools faster at night and the waters are warmer
Warm air over water rises
Cool air over land sinks
Land breeze moves out over water to replace warm air

20. Precipitation Water which can change form in the atmosphere.
Solid or liquid form (depends on ground and air temperatures).
Found in cumulus clouds.
Made via condensation, freezing and sublimation.

21. Dew
Created when moisture in air contains condenses on a cool surface near the ground.
Frost
sublimation on a very cold surface.
Drizzle
Fine water droplets
Less than 0.5 mm in diameter.

22. Hail Forms in troposphere (in thunder clouds)
Ice pellets move up and down in troposphere.
Each rise upward passes them through cold water droplets.
They grow larger as the freezing water droplets form more and more ice layers (~ 20 layers).

24. Ice pellets/sleet Rain Freezing rain Small hard pieces of ice.
Formed as
Snow falls through layer of warm air and melts a little.
It them passes through cold air and re-freezes.
Rain
Falling water droplets
Up to 5mm in diameter.
Freezing rain
Rain that hits a very cold surface and freezes immediately.

25. Snow Forms when air temp is below 0 degrees Celsius.
Water vapour crystallize on dust or other particles.
Ice crystals combine and form snow flakes.
(may turn into sleet/ ice pellets) if it passes through warm air then cold again.

26. Meteorological data is collect using:
Thermometers: temperatures
Hydrometer/psychrometer: humidity
Aneroid barometer: barometric/air pressure
Anemometer: wind speed, direction
Rain gauge: level of precipiatation