Lecture 11: Changing Winds: Global Climatic Change
What does climate mean?
Climate vs. weather
•Weather- what is it like outside?
oWhat is it usually like outside?
oDescription of typical weather conditions for location and time of year
oBased on statistics accumulated over long period of time (at least 30 years)
•Timeframe between weather and climate
•To know weather, have to have a sense of climate of particular region
Toronto’s climate for July
•30 years mean climate of Toronto is 22.2
•Weather can report max, min temperature and rain
•To report extremes, need more time period change of temperature- climate
•Midlatitude cities have the most distinct 4 seasons
What factors influence climate?
oIncident radiation from sun
oHow much sunlight you get in terms of which latitude you are in
oIn subtropics, they get almost 2 hrs less of sunlight than Toronto
oPrevailing winds, jet streams, ocean currents
oBecause position of jet stream, we sometimes feel milder/colder winter
oTransport of warm or cold, moist or dry air
oKnown 7 air masses, they affect climate of North America
oGeography of Toronto is unique because we have Oakridge moraine surrounding the city,
preventing Toronto from getting all the lake affect snow
oAlbedo, evepotranspiration, heat capacity
oHigher amount of precipitation
What is a feedback?
•Change in A will cause change in B, that change in B will cause change in A in that same direction
it is called position feedback, if opposite direction- negative feedback
•Highest Albedo for fresh snow
•Thick clouds are higher reflective
•Thin clouds have lower Albedo
•Warming causes reduction of ice and snow, less ice and snow reduces reflectivity, which causes
more warming= positive feedback
•Increase temperature increase water vapour increase in temperature