4.1 Climate page 96-98

Assignment Work: Answer Q 1abc 2ab on pg 98

Weather and Climate

• Weather – day to day condition of Earth’s atmosphere.

• Climate – average conditions over long periods. – temperature and precipitation

• Microclimates – varying conditions within region. – EX: in N hemisphere – S hotter and drier

Factors that affect climate

• Global Climate– 1. Solar energy trapped in biosphere– 2. Latitude– 3. Transport of heat by winds and ocean currents

1. Solar Energy and Greenhouse Effect

• Sun strikes Earth• Some is reflected back to space or converted

to heat.• Some heat radiates back to space or trapped

in biosphere• Balance determines Earth’s average

temperature• Gases that control in atmosphere are carbon

dioxide, methane, water vapor.

• These gases are greenhouse gases. • Greenhouse effect – allows visible light to

enter but traps heat.• If more gasses – trap heat and Earth warms• If less gases – heat escapes and Earth cools.• Without them Earth would be 30 degrees C

cooler.

2. Latitude and Solar Energy

• Equator- sun is intense • Poles – less solar energy and heat• Curvature of Earth causes same amt of solar

energy to spread towards the poles. • 3 zones: – Tropical , Temperate, Polar

3. Heat Transport in Biosphere Winds…• Unequal distribution of heat across globe

creates wind and ocean currents.• These transport heat and moisture. • Winds: Warm air is less dense and rises

(equator), Cool air is more dense and sinks (poles).

• Earth’s rotation causes winds to blow – west to east = temperate zones. – East to west = tropics and poles.

Oceans..• Ocean surface water is pushed by winds• Currents transport heat• Warm = add moisture and heat to air • Cool = cool the air • Currents affect weather and climate of nearby

landmasses. • Deep ocean currents are caused by cold water near

the poles sinking and flowing along ocean floor. • This water rises in warmer regions through a

process called upwelling.

El Nino and La Nina• El Nino Weather -is the warming of water in the Pacific Ocean.

– Rain and flooding along the Pacific coast – Warm water disrupts food chain of fish, birds, and sea mammals – Tornadoes and thunderstorms in southern US – Fewer than normal hurricanes in the Atlantic

• La Nina Weather -is the cooling of water in the Pacific Ocean. – Snow and rain on the west coast – Unusually cold weather in Alaska – Unusually warm weather in the rest of the USA – Drought in the southwest – Higher than normal number of hurricanes in the Atlantic

• El Nino and La Nina are the most powerful phenomenon on the earth and alter the climate across more than half the planet.

• Map• In a 1998 report, scientists from NOAA explained

that higher global temperatures might be increasing evaporation from land and adding moisture to the air, thus intensifying the storms and floods associated with El Niño.

Weather in Ohio- Great Lakes• The Great Lakes have a big influence on the climate.

• Acting as a giant heat sink, the lakes moderate the temperatures of the surrounding land, cooling the summers and warming the winters.

• This results in a milder climate in portions of the basin compared to other locations of similar latitude.

• The lakes also act as a giant humidifier, increasing the moisture content of the air throughout the year.

• In the winter, this moisture condenses as snow when it reaches the land, creating heavy snowfall in some areas, known as "snow belts" on the downwind shores of the lakes.

• The shores of Lake Superior are prone to this "lake effect" snow and have recorded up to 350 inches of snow in a single year.

• During the winter, the temperature of the lakes continues to drop. Ice frequently covers Lake Erie but seldom fully covers the other lakes.