The Earth’s surface, especially water, has a HUGE influence on our climate and weather.

  70% of Earth’s surface is covered with water Water plays a major role in the absorption and distribution of thermal energy, influencing both weather and climate: the great moderator

The amount of heat (J) required to raise the temperature of 1 g of a substance by 1 o C

  It takes a lot of solar radiation to heat water, so water is a heat sink. It absorbs a great deal of solar radiation, keeping the region cooler during the day, and it slowly reradiates the heat at night

SUBSTANCE Pure water Steam Ice Sea water Moist air Dry air c (J /g o C) 4.19

2.02

2.00

3.89

1.15

1.00

Pg. 375

Q = mcΔT

c = specific heat capacity J/g o C ΔT = change in temperature o C m = mass g Q = amount of heat J If data are given in initial (T 1 ) and final (T 2 ) temperatures instead of change in temperature, calculate ΔT using ΔT = T 2 – T 1

 Model Problems A and B, pg. 376  Do Practice Problems #1 – 9 pg. 377

  a) The Earth’s land or water surface heats up as it absorbs solar radiation.

b) This thermal energy is transferred by conduction to surrounding cooler air or water causing convection currents in air and water

 Convection (transfer of thermal energy in fluids – liquids or gases) Convection currents – air circulates and distributes heat (remember warm air is less dense, rises, cooler air descends and takes its place close to the ground, it heats up…etc.

 Different specific heat capacities of the Earth’s different surfaces (sand, water, forests, etc) affect how much they heat up the air and water around them.

Why is the ice and water absorbing energy with no change in temperature?

 The Earth’s water absorbs a lot of heat from the surroundings when condensing, and it releases a lot of heat when it is evaporating.

 Heat of vaporization (H (evaportate it) vap ) is the amount of thermal energy required to convert one mole of a substance from a liquid to a gas  Heat of fusion (H fus ) is the amount of thermal energy required to convert one mole of a substance from a solid to a liquid (melt it)

    Energy required for melting Energy required for vaporizing  Q = nH fus Q = nH vap Q amount of heat energy n number of moles H fus H vap heat of fusion heat of vaporization J (joules) (no units) J/mol J/mol

 Practice Problems 10 – 18 pg. 383

  The hydrologic cycle distributes water by evaporation, condensation, and precipitation.

It transports thermal energy as well. When water condenses, thermal energy is released, when water evaporates it absorbs thermal energy affecting weather and climate

 Specific Heat Practice problems # 1-9 pg. 377  Heat of fusion and vaporization problems #10-18 pg. 383  Questions: Pg. 387 #1, pg. 398 #11, 12 (question # 13 gives you hints), 14, 16