Climate and Climate Change Weather vs Climate Weather

Climate and Climate Change

Weather vs. Climate • Weather – state of the atmosphere at a given time and place • Climate – long term prevailing weather conditions based on historical data

Factors that Determine Climate • Latitude – Distance North or South of the equator (0 o) • North Pole (90 o. N) – Low latitudes (near equator) • Solar energy concentrated on small area • Night/Day = ~12 hours – High latitudes (near poles) • Sun hits at an oblique angle – distributes solar energy over large area

Factors that Determine Climate • Atmospheric circulation – Cold, dense air sinks compresses and warms – Warm, less dense air rises • Holds more water vapor than cold air – Clouds form when it cools (after rising) – Sun heats earth warms air it rises replaced by cooler air • Wind

Factors that Determine Climate – Prevailing winds • Direction of wind throughout the year – Don’t move directly N or S » Deflected due to Earth’s rotation » To the right in northern hemisphere » Left in southern

Factors that Determine Climate • Oceanic Circulation Patterns – Ocean holds large amount of heat – Affected by wind and rotation of earth – Distribute warm/cold masses of water – Special circumstances • El Nino http: //oceanservice. noaa. gov/f acts/ninonina. html • La Nina https: //www. youtube. com/watch? v=5 q. Pibjwo 21 g http: //www. cnbc. com/2016/01/08/severe-el-nino-puts-world-in-uncharted-territory-un. html

Southern Oscillation • Winds normally travel E W in the tropical Pacific (trade winds) – From high pressure area in Eastern Pacific – To low pressure area in Western Pacific • 3 to 8 years these pressure areas change – Reasons unknown • Winds travel in opposite direction (W E) – Southern Oscillation

Factors that Determine Climate • Topography – Mountains influence precipitation • Rain shadow – Warm air forced to rise cool precipitation dry air

Factors that Determine Climate • Seasonal changes – Tilt of Earth’s axis (23. 5 o) • Angle of sun’s energy changes – Summer – northern hemisphere tilted towards the sun » Receives direct sunlight

The Ozone Layer • Ozone = O 3 – Ozone layer • Absorbs most UV light from sun – Harmful to plants and animals – Natural sunscreen

Harmful Chemicals • Chlorofluorocarbons (CFCs) – Harmless, very stable • Coolant, spray cans – Break apart in upper atmosphere • Cl atoms destroy O 3 – 1 Cl can destroy 100, 000 O 3

Ozone Hole • Thinning of stratosphere over Antarctica during the spring – Reported a few years after CFCs became widely used • Some areas are over 50% lost

Effects on Life • Loss of ozone layer more UV light reaches earth more mutations – Humans • Cancer • Weakened immune response – Marine life • Kills primary producers (less photosynthesis) – Land plats • Interferes with photosynthesis • Reduced crop yield

Can We Change It? • Montreal Protocol (1987) – International agreement to protect ozone layer • US agreed to ban all substances that pose a significant danger by 2000 • CFC production has decreased worldwide • CFCs remain active for 60 -120 years – Will take a long time to repair