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? 1.Annual precipitation of 200 mm. 2.Rain forecasted for tomorrow. 3.Normal July temperature averages 22 o C. 4.Temperatures this week will range between 20 & 30 o C. 5.It was unusually hot this summer. 6.Vancouver has an annual frost free period of 233 days. 7.The greatest annual precipitation 11, 680 mm falls on Mt. Waialeaie in Hawaii. 8.Residents in Florida are preparing to take shelter from a hurricane. Climate Weather Climate Weather Climate Climate Climate Weather

In describing today’s weather: 9 features are often used!! 1.Temperature 2.Amount of precipitation 3.Type of precipitation 4.Atmospheric pressure 5.Wind direction 6.Wind speed 7.Cloud cover 8.Hours of sunshine 9.Humidity

Explain why only about ½ of the sunlight directed at earth actually reaches the earth.

6% is scattered in the atmosphere 24 % is reflected by clouds 4 % is reflected by the earth’s surface. 17 % is absorbed by Green House gases & dust 49% of sun’s radiation actually reaches the earth’s surface

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 nightly temperatures. (heat escapes, nothing to TRAP it.) Ex. Day 24 o C, Night 15 o 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 24 o C, Night 21 o 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 COLDER nightly temperatures. Already cooler temperatures become even lower. Ex. Day 15 o C, Night 9 o 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 in the night. Clouds traps current air temperatures and keeps them relatively constant. Ex. Day 15 o C, Night 12 o 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)