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Weather dynamics
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- 2. SOME GENERAL TERMS •WEATHER DYNAMICS is the study of how water and air cause weather patterns. • WEATHER – The short-range forecast; daily conditions. – Ex: temperature, precipitation, wind, humidity, UV • CLIMATE – Long-term seasonal trends averaged from annual data – Ex: In the Atlantic Canada Climate region, winters are cold and summers are Warm
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- 4. What is theAtmosphere? DEFINITION: • The blanket of air and water vapour that surrounds the Earth. • If the earth were an ONION, the atmosphere would be like the ONION PEEL. • It is about 500 km thick, containing 78% N , 21% O , and some trace elements (ex: CO2, H2O, Ar).
- 5. LAYERS OF THEATMOSPHERE • Defined according to ALTITUDE, or elevation above sea level. • TROPOSPHERE – 8-16 km altitude, layer closest to earth’s surface – This layer is the most dense, meaning it contains the most particles. – Weather occurs in this layer. – Temperature ranges from 20 to -50degrees Celsius. – The tropopause is on the upper end of this layer.
- 6. ATMOSPHERIC PRESSURE • Definedas the pressure that air particles exert as gravity pulls them toward the centre of the earth • Air pressure is greatest at sea level where air is most dense (i.e., thick) • Air pressure decreases with altitude. – Thus, if you climb a mountain, the weight of the air above you is less, and the pressure is less.
- 7. WINDS • Wind isthe movement of air in the atmosphere. – Some winds are local while others are prevailing. • Local winds occur in a fairly small region. • Prevailing winds are wind patterns that affect large regions around the world.
- 8. PREVAILING WINDS • Inthe early 1800s, SAILORS discovered that, in certain areas, the winds blow in the same direction all of the time.
- 9. THE CORIOLIS EFFECT •The change of DIRECTIONof a moving object in a constantly rotating system. • The rotation of the EARTH deflects moving air AND water to the RIGHT of its initial direction in the Northern Hemisphere (opposite in the Southern Hemisphere). – Note: • This direction of deflection is from the viewpoint of the starting position of WHAT IS BEING DEFLECTED (ex: plane, wind, etc.). – FIGURE 2 - pg. 517 – FIGURE 1 - pg. 525
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- 11. Prevailing Winds inthe Northern Hemisphere • Prevailing Winds help distribute energy and moisture around the globe. • TYPES IN NORTHERN HEMISPHERE – Polar Easterlies • Cold easterly winds blow from the poles to 60 degrees. – Mid-Latitude Westerlies • Warm, moist winds blow from the west • NEWFOUNDLAND is affected by these. – North East Trade Winds • Winds that blow toward the equator
- 12. JET STREAMS • Fastmoving riversof air that race across the high altitude sky, sometimes at speeds as high as 400 km/h. • Jet streams occur about 7000 m up in the upper regions of the troposphere. • They consist mostly of westerly winds, and are caused by strong differences in pressure and temperature. • Air at the equator is thickerand moves from high to low pressure areas (i.e., N or S of the equator). • Jet streams can be thousands of miles long, hundreds of miles wide, but only a mile or so deep.
- 13. JET STREAMS • Pilotscan reduce flight time by hitching a ride on a jet stream. • Long lines of clouds often indicate the presence of a jet stream.
- 14. MAJOR OCEAN CURRENTS •Oceans have a HUGE effect on weather patterns. Here are just a few of the ways water is significant in this regard: – Oceans are heat sinks since most of the sun’s direct rays hit water. – If water is warm, air above it is warm, meaning lots of moisture. If water is cold, air above it is cold. – Warm water is constantly moving from the equator to the poles. – Cold water is constantly moving from the poles to the equator.
- 15. MAJOR OCEAN CURRENTS •Which ones influence NEWFOUNDLAND weather? __________________________
- 16. WHAT CAUSES OCEANCURRENTS? • Convection currents • Winds across oceans • Earth’s rotation • Shape of continents • Heat capacity of Water • Amount of salt in oceans