Chapter 6

Weather and Climate Weather refers to the day to day conditions of the atmosphere in a specific area Climate describes the weather conditions that occur in a specific area over a long period of time. Meteorologist is a weather specialist Humidity refers to the amount of moisture in the air and is measured as a percentage Precipitation is all the moisture that falls from the sky

Weather and Its Influences Weather affects our lives daily Sometimes the conditions can be extreme and cause natural disasters Impact of weather is not always dramatic Plants and animals are also influenced by the conditions of the atmosphere

Humidex used to measure the combined effect of temperature and humidity Wind Chill factor measures the chilling effect on human skin of the wind combined with cold temperatures Ultraviolet (UV) rays can damage the eyes and burn deeply into unprotected skin Health Indicators

Humidex

Wind Chill

Weather Patterns across Canada Geographers search for patterns so that they can predict changes to the Earth’s surface Identifying weather patterns make it easier to predict tomorrow’s weather Weather patterns follow a general pattern

Weather Patterns across Canada (cont.) In Canada, places near Atlantic and Pacific Ocean are wetter Prince Rupert, BC is the wettest, receives precipitation for over 300 days a year Winter weather is milder West Coast temperatures rarely drop below freezing

Weather Patterns across Canada (cont.) Interior of Canada and far North Enjoy more hours of sunshine Receive less precipitation Real extreme in temperatures Hot summers and cold winters

How Air Masses Affect the Weather Air masses are large bodies of air with particular temperature and moisture characteristics Warm front is when warm, moist air from the Gulf of Mexico moves north Cold front is when cold, dry air from the Arctic moves southward

How Air Masses Affect the Weather (cont.) Communities near the Great Lakes have changeable weather Different types of air masses push into regions from different directions Warm front rides up over cooler air in front of it causing clouds to form and is often followed by precipitation Cold front pushes warm moist air upward and causes dark clouds to form and is often followed by powerful thunder and lightening storm.

Canada’s “Storm of the Century” Early 1998 Eastern Ontario and Southern Quebec 5 continuous days of freezing rain Large warm air mass from Gulf of Mexico swept northeastward by a high speed wind (jet stream) In southern Canada, it met a cold air mass and rode up over it Clouds and rain developed, and the water droplets froze wherever they landed

Canada’s “Storm of the Century” Weight of ice caused trees and hydro towers to break Over 2 million people left without power in the middle of winter 25 deaths At least half a billion dollars damage Widespread environmental destruction

How the Oceans affect the Weather El Nino Spanish for “boy child” Warm Pacific Ocean current that reaches the coast of Peru during December Sometimes the water is warmer than usual and causes great changes in weather over North and South America Warm ocean water evaporates more quickly and results in more clouds and precipitation During El Nino winters Canada has milder conditions and rain often replaces snow

How the Oceans affect the Weather (cont.) La Nina Spanish for “girl child” Large pool of cold water appears off the Pacific coast of South America Results in colder and snowier weather in Western Canada