Lecture 7 - Weather Flashcards
What are the three main types of energy?
Potential - stored energy
Kinetic - energy of motion
Heat - energy of random motion of particles
What are the two important types of heat?
Sensible - able to detect it
Latent - heat released or absorbed when a substance changes state
What are the three types of heat transfer?
Conduction - through a materal
Convection - through the movement of a fluid
Radiation - through electromagnetic waves
Nearly all the energy on earth comes from the ____
Sun
Redirection?
When energy reflects off of a surface (ex. off of clouds, water, land)
Transmission?
When energy goes through the atmosphere
Absorption?
Alters the structure of molecules (causes them to vibrate and emite energy in the form of heat or electromagnetic waves)
Albedo?
The reflectivity of a surface
What type of surface has the highest albedo?
Light coloured surface - best at reflecting
EXAM Q: what percent reflectivity is old snow?
50-60%
Selective absorber?
Absorb some wavelengths but emit others
- Co2 and water vapour selectively absorb infrared waves
What type of wavelength does the sun radiate?
Short - hot, high energy
What type of wavelength does the earth radiate?
Long - cool, low energy
Atmosphere?
Thin envelope of gases the surrounds the Earth
What makes up the atmosphere?
Nitrogen, oxygen, smaller amounts of argon, water vapour, and carbon dioxide
Humidity
The amount of water vapour in the atmosphere ata specific temperature
What are the 4 layers of the atmosphere?
- Troposphere (8-16km above the surface, we interact with this one the most)
- Stratosphere
- Mesosphere
- Thermosphere
What is the name for the boundary at the upper limit of the troposphere?
Tropopause
Cumulus?
Fluffy good weather cloud
Cumulonimbus?
Dark, towering thunderstorm cloud
Another name for atmospheric pressure?
Barometric pressure
Atmospheric pressure?
The weight of a column of air above a point on or above earth’s surface
Where is atmospheric pressure the higher/lower?
Higher at sea level and lower at the top of a mountain
What causes wind to blow?
Variations in temperature, air movement, and water vapor
Air is warm and low in density at the _____
Equator
Air is cold and more dense at the _____
Poles
Pressure gradient?
Difference in pressure between the poles and the equator
- Flows from high P to low P (poles to eq)
- Temp diff causes pressure diff causes wind
Atmospheric stability?
The tendency of a parcel of air to remain in place or to change its vertical position
An air mass is stable if ____
It’s parcels resist vertical movement or return to their original position after they move
An air mass is unstable if ______
it’s parcels rise until they reach air of similar temperauter and density
Cold front?
When cool air moves into a mass of warm air
Warm front?
When warm air moves into a mass of cold air
Stationary front?
Has a boundary that shows little movement (between hot and cold)
Occluded front?
When cold air moves into a mass of warm air with another mass of cold air behind it
Where do thunderstorms mostly occur?
Equatorial regions
What are the three conditions required for thunderstorms?
- Water vapour in the troposphere
- Updraft
- Temperature gradient in the troposphere
How is a thunderstorm formed?
Moist hot air is forced upwards, cools, and water vapour condenses to form a cumulus cloud
What are the three stages of a thunderstorm?
- Cumulus stage: cloud grows upwards, continuous release of latent heat from condensation warms surrounding air
- Mature stage: downdrafts and falling precipitation leave the base of the cloud, grows until it hits the tropopause, intense precipitation, thunder and lighting
- Dissipative stage: upward supply of moist air is blocked by downdrafts, thunderstorm weakens and dissapates
How long do most thunderstorms last?
an hour
How does precipitation start in a thunderstorm?
- Cold air: ice crystals and snowflakes fall until they melt
- Warm air: larger and smaller droplets collide and combine
What classifies a thunderstorm as severe?
One of the following:
- Wind speeds in excess of 90km/h
- Hair bigger than 1.5 cm
- It generates a tornado
Hail?
Hard pieces of ice coming from thunderstorms, formed when a hailstone moves up and down in the lower part of the storm
Tornados
A vortex extending downward from a cloud and touching the ground
Funnel cloud?
When the vortex doesn’t touch the ground
What is required to form a tornado?
- Wind shear
- Updrafts
What occurs in the organizational state of a tornado?
Wind shear makes the air rotate, updrafts tilt the rotating air, and if they are strong enough they will form a mesocyclone and eventually a wall cloud forms, from which a funnel cloud may descend
What occurs in the mature state of a tornado?
Visible condensation funnel extends from the clud to the ground, moist air drawn upwards, suction vortices (intense whirls) may form
What occurs in the shrinking and rope stages of a tornado?
Suppoy of warm moist air is reduced, funnel tilts, downdrafts cause the funnel to dissipate
EXAM Q: what scale number and windspeed is classified as “considerable damage” for a tornado
EF2 - 178km-218km
Blizzard?
Severe winter
What is the threshold for blizzard conditions in Canada?
40km winds, visibility is 400m, for 4 hours
Alberta Clippers?
Fast moving drier storms (blizzards), cold temperatures
Nor’easters?
Heavy snow storms with hurricane force winds, high snowfall, and high waves, found only on the east coast of North America
Wind chill?
Moving air rapidly cools exposed skin by evaporing moisture and removing warm air next to the body
Extreme cold?
Varies depending on the climate average/community preparedness
Ice Storms?
Prolonged periods of freezing rain, the rain freezes upon impact
What does an ice storm require?
- North side of a warm/stationary front
- Moisture on the south of the front
- Warm air overlies a shallow layer of cold air
- Objects on ground are at or below freezing temp
Fog?
A cloud in contact with the ground, forms by air cooling to condensation or by the evaporative addition of water vapour in already cool air
Drought?
An extended period of unusually low precipitation
- over a billion people live in semi-arid regions where drought is more common
Dust/Sand storms?
Strong windstorms that transport sediment, req. wind velocity to exceed 48 km/hr, visibility to be less than 800m
Heat Waves?
Periods of heat that are longer and hotter than normal, can be humid or dry
Humidex/Heat Index?
Measures the body’s perception of air temperature
