Global Warming Learning goal: determine the long term impact of humans on weather and vise versa

What is Global Warming? Increasing air temp because of heat being trapped in the atmosphere caused by greenhouse gases, such as CO 2 Earth is starting to warm because less heat is being released back into space Humans burning fossil fuels such as gas and coal are primarily responsible CO 2 is released in huge amounts when we drive cars, burn coal to generate electricity, and produce goods in factories Increasing air temp because of heat being trapped in the atmosphere caused by greenhouse gases, such as CO 2 Earth is starting to warm because less heat is being released back into space Humans burning fossil fuels such as gas and coal are primarily responsible CO 2 is released in huge amounts when we drive cars, burn coal to generate electricity, and produce goods in factories

How Does Solar Energy Move? Energy comes to Earth by RADIATION... Then gets transferred all 3 ways: Radiation (energy that travels from a source) Conduction (energy that’s transferred by contact) Convection (energy transfer in moving fluids)

Insolation Facts Only 51% of solar energy reaches Earth’s surface Much of that is radiated back into atmosphere through infrared radiation CO 2 absorbs much of this infrared radiation, trapping the heat in our atmosphere This is called the Greenhouse Effect Without natural Greenhouse Effect Earth would be freezing (60 degrees F cooler) Enhanced Greenhouse Effect makes temps increase with possibly disastrous results Only 51% of solar energy reaches Earth’s surface Much of that is radiated back into atmosphere through infrared radiation CO 2 absorbs much of this infrared radiation, trapping the heat in our atmosphere This is called the Greenhouse Effect Without natural Greenhouse Effect Earth would be freezing (60 degrees F cooler) Enhanced Greenhouse Effect makes temps increase with possibly disastrous results

Factors Affecting Insolation Tilt of the Earth (23.5 deg) Earth is heated unevenly, causing temp to vary around the world Different latitudes receive more or less energy Equator hottest – Poles the coldest Time of Day Closest to 90° at noon, warmest in afternoon, coldest just before sunrise Tilt of the Earth (23.5 deg) Earth is heated unevenly, causing temp to vary around the world Different latitudes receive more or less energy Equator hottest – Poles the coldest Time of Day Closest to 90° at noon, warmest in afternoon, coldest just before sunrise

Factors Affecting Insolation Season (time of year) Northern Hemisphere has highest temperature just after time of maximum insolation June 21 (summer solstice – longest day) Lowest temp at time of minimum insolation December 21 (winter solstice – shortest day) Season (time of year) Northern Hemisphere has highest temperature just after time of maximum insolation June 21 (summer solstice – longest day) Lowest temp at time of minimum insolation December 21 (winter solstice – shortest day)

Factors Affecting Insolation Cloud Cover Clouds reflect insolation back into space More solar energy reaches Earth on clear days More infrared radiation (from the surface) travels back into space on clear nights Cloud Cover Clouds reflect insolation back into space More solar energy reaches Earth on clear days More infrared radiation (from the surface) travels back into space on clear nights

Heating of Water and Land Water and Land heat up and cool off at different rates Water heats more slowly than land Why? Heat goes deeper in water than land Water spreads heat easily by convection Some solar radiation is used in evaporation Water needs more energy than land to raise temperature Water and Land heat up and cool off at different rates Water heats more slowly than land Why? Heat goes deeper in water than land Water spreads heat easily by convection Some solar radiation is used in evaporation Water needs more energy than land to raise temperature

Heating of Water and Land Varying types of land absorb heat differently Dark surfaces absorb more energy Rough surfaces absorb more energy Wet ground warms more slowly Meadows are warmer than forests Cities typically have higher temps than forests Why? Building materials like concrete & asphalt absorb & radiate enormous amount of heat (urban heat island) Varying types of land absorb heat differently Dark surfaces absorb more energy Rough surfaces absorb more energy Wet ground warms more slowly Meadows are warmer than forests Cities typically have higher temps than forests Why? Building materials like concrete & asphalt absorb & radiate enormous amount of heat (urban heat island)

The Effects of Ice Ice reflects sunlight, and thus radiation, back into space Cooler temperatures More snow cover Less energy absorbed from the sun Warmer temperatures Less snow cover More energy absorbed from the sun

The Effects of Water Honolulu, Hawaii Latitude: Jan temp: 73 F San Diego, California Latitude: Jan temp: 57.8 F Latitudes are different but temps are moderate because they are surrounded by or next to the ocean Honolulu, Hawaii Latitude: Jan temp: 73 F San Diego, California Latitude: Jan temp: 57.8 F Latitudes are different but temps are moderate because they are surrounded by or next to the ocean San Diego

Heating of Land San Diego, California Latitude: Jan temp: 57.8 F Phoenix, Arizona Latitude: Jan temp: 54.2 F Latitudes are very similar but temperatures over land masses can vary greatly San Diego, California Latitude: Jan temp: 57.8 F Phoenix, Arizona Latitude: Jan temp: 54.2 F Latitudes are very similar but temperatures over land masses can vary greatly July temperatures San Diego: 70.9 F Seasonal change: 13.1 deg F Phoenix: 92.8 F Seasonal change: 38.6 deg F July temperatures San Diego: 70.9 F Seasonal change: 13.1 deg F Phoenix: 92.8 F Seasonal change: 38.6 deg F