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Learn to differentiate between weather and climate and explore factors influencing temperature variation from day to night. Discover how cloud cover affects temperature range and why only a portion of sunlight reaches the Earth's surface.
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Unit 2 World Climate Patterns… An Introduction
Distinguish between the terms weather & climate. P. 54 • Weather = the state of the atmosphere at any one place or time. (short term) • Climate = the average weather conditions of a region over the LONG term. (Season, Month Annually) • Both refer to temperature, rain fall, humidity etc.
Practice:Do the following phrases refer to weather or climate? Climate Weather Climate Weather Climate Climate Climate Weather • Annual precipitation of 200 mm. • Rain forecasted for tomorrow. • Normal July temperature averages 22 oC. • Temperatures this week will range between 20 & 30 oC. • It was unusually hot this summer. • Vancouver has an annual frost free period of 233 days. • The greatest annual precipitation 11, 680 mm falls on Mt. Waialeaie in Hawaii. • Residents in Florida are preparing to take shelter from a hurricane.
In describing today’s weather: 9 features are often used!! • Temperature • Amount of precipitation • Type of precipitation • Atmospheric pressure • Wind direction • Wind speed • Cloud cover • Hours of sunshine • Humidity
Explain why only about ½ of the sunlight directed at earth actually reaches the earth.
49% of sun’s radiation actually reaches the earth’s surface • 6% is scatteredin the atmosphere • 24 % is reflected by clouds • 4 % is reflected by the earth’s surface. • 17 % is absorbed by Green House gases & dust
While the 4 % that reflects from the earth’s surface is small it does vary with location & with time. How/Why do you think it varies? • Winter vs. Summer? • Poles Vs. equator? • Land vs. ocean? • HINT: Precipitation (Snow & water), reflection vs absorption, dust, cloud cover, angle of sun,
Lack of cloud cover Day AND Night… the effect… • DAY : No clouds = higher day temperatures • NO clouds to deflect / block heat from reaching the surface. • NIGHT:NO cloud cover = cold nightlytemperatures.(heat escapes, nothing to TRAP it.) • Ex. Day 24o C, Night 15o C
Clear Day AND clouds over BEFORE night…the effect… • DAY : No clouds = higher day temperatures • NO clouds to deflect / block heat from reaching the surface. • cloud cover PRIOR to night = = warmer and muggy nights. • heat being TRAPPED during the night…like a blanket AND precipitation in the clouds. • Ex. Day 24o C, Night 21o C
Cloudy Day AND NO clouds at Night… the effect… • DAY : Cloud cover = lower daily temperatures • Clouds deflect/block out sun & heat. • NIGHT : NO cloud cover = even COLDERnightly temperatures. • Already cooler temperatures become even lower. • Ex. Day 15o C, Night 9o C
Cloudy Day AND cloudy Night…the effect… • Day: Cloud cover = lower daily temperatures • Clouds deflects/blocks out heat • Night:Cloud cover = relatively constant temperatures inthenight. • Clouds traps current air temperatures and keeps them relatively constant. • Ex. Day 15o C, Night 12o C
Explain how cloud cover influences the range of temperature from day to night. • Clear day / Clear Night = largest temp range (24–15=9) • Clear day, cloudy night = small/low temp range (24-21=3) • Cloudy day, clear night = moderate range (15-9=6) • Cloudy day / cloudy night = small temp range(15-12=3)