Science 10 – Weather Day 4 - Water

Water Is A Heat Sink WHY? Water covers 70% of the Earth's surface Rivers, lakes and oceans absorb 93% of the radiation from the sun but their temperature doesn't increase very much WHY?

Background Info Specific heat capacity = energy required to raise 1g of a substance by 1°C Specific heat capacities (en J/g°C): Water: 4.18 Dry air: 1.00 Wet mud: 2.51 Brick: 0.84

What do you think? Imagine 3 cups that you are heating on a burner. Each cup contains the same amount of a substance (100g) Cup 1 = alcohol (c = 2.46 J/g°C) Cup 2 = water (c= 4.18 J/g°C) Cup 3 = vegetable oil (c = 2.00 J/g°C)

Which liquid could you touch even after you’ve started heating? 3 – veg oil c = 2.00 J/g°C 1 – alcohol c = 2.46 J/g°C 2 – water c= 4.18 J/g°C Which liquid could you touch even after you’ve started heating? After being heated, which would cool off first?

http://www.youtube.com/watch?v=_6rb_WkRJoo&feature=related Why doesn't the water balloon burst?

What does that mean? The higher the specific heat capacity, the ___________ energy is needed to raise the temperature.

Water heats & cools slowly This property of water explains why coastal regions have a moderate climate (few drastic temperature changes): bodies of water make temperature changes gradual

Water & Temperature A lot of energy is needed to melt water (solid → liquid) or evaporate it (liquid → gas) . This is why it takes a long time for the temperature in the spring to rise significantly even if the days are longer and there is more sunlight Most of the sun's energy is used to melt snow/ ice Solidifying water (freezing it) releases a lot of energy (liquid → solid). This is also why the temperature falls slowly in autumn even though there is significantly less sunlight Changing liquid water into ice releases heat

Virtual Lab Why is water a heat sink? http://oceanservice.noaa.gov/education/pd/oceans_weather_climate/media/specific_heat.swf

Heat sink A substance that can absorb and retain heat, without changing its temperature/state Substances with high heat capacity ex. Water

wind from the sea towards land Land & Sea Breezes Sun = day During the day: -Air above the ground is warmer (soil heats more quickly than the water) -Warm air rises, creating a low pressure space above land, then travels towards the sea, cools off, sinks. -Wind moves sea air in to fill low pressure space = sea breeze Sea breeze: wind from the sea towards land

wind from the land towards the sea Land and sea breezes Moon = night During the night: -Air above the sea is warmest (water cools more slowly) -Warm air rises, creating a low pressure above the water, moves towards the land, cools and falls -Wind moves air out to the water to fill the low pressure space = land breeze Land breezes: wind from the land towards the sea