Transcript Surface Water and Climate

As we are reading remember to make connections with
the text. They will help you to remember and understand
the information more!
What is the difference between
weather and climate?
 Weather:
 Climate:
Causes of Temperature Differences
 We already know that energy from the sun drives the
evaporation of water in the water cycle, right?
 Well it is also responsible for heating the Earth’s surface
 At night, when the sun dips below the Earth’s horizon, the
earth cools down as it radiates more energy than it
absorbs
 This change form daytime heating to night-time cooling is
so dramatic on most planets that they can not support
life...neat!
Heat Capacity
 So why does Earth support life better than other planets?
 Well... Part of the answer lies in the substances that make
up the Earth’s surface: water, soil and rock, AND an
important property of these substances called HEAT
CAPACITY.
 Heat Capacity is a measure of how much thermal energy
(heat) a substance requires to increase its temperature
by a certain amount.
Heat Capacity (H.C.) – The Goods!
 The HIGHER the H.C., the more thermal energy it can
store!
 Soil and rock have LOWER heat capacities than water –
this means that it takes LESS thermal energy to increase
the temperature of rock or soil than it does to increase
the temperature of water.
 Let’s talk about a day on the beach...
 H.C. also includes the amount of thermal energy (heat)
that a substance releases!
 If thermal energy is removed from soil or rock, they
would begin to release their stored thermal energy to the
surrounding air.
 Because of their low H.C., energy would be released
quickly – causing them to cool down and heat the
surrounding area quickly.
 BUT, once the soil or rock had cooled, it would no longer
be able to heat the air, and the air would begin to cool.
 Remember how we said that water has a HIGHER heat
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capacity than rock or soil....well here is where it get’s
interesting!
Because of it’s HIGH H.C. water releases it’s stored
thermal energy at a MUCH slower rate.
This means that water heats the air much more slowly
around it, BUT for a much longer time!
Water can store energy for a very long time – even if the
air above it cools at night, or if the seasons change!
Remember our beach example – let’s expand on that with
PIZZA! (the non-whole wheat crust kind!)
Heat Sinks
 Anything that absorbs thermal energy WITHOUT becoming
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much warmer is called a heat sink.
Think – High heat capacity = Good heat sink!
Water absorbs energy, but it is continually moving and mixing
– therefore the energy is transferred throughout the entire
body of water. This is what prevents the ocean water from
heating up. (Connection – desalination)
Land gives up stored thermal energy much more rapidly than
water.
When the sun goes down, or when the days get shorter in the
winter, land cools more rapidly than water.
Let’s look at the temperature differences
between inland and coastal cities.
Victoria
Winnipeg
Timmins
St. John’s
Avg. January minimum
temperature (°C)
2
-22
-24
-7
Avg. July maximum
temperature (°C)
20
27
24
21
 You would expect each of the cities to receive the same
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amount of energy from the sun
However, the inland cities are colder in the winter and
warmer in the summer than the coastal cities – Why???
Land near water has a milder climate than land far from
water because bodies of water act as heat sinks.
Coastal cities are warmer in the winter and cooler in the
summer than inland cities
Do you think Ontario’s climate can be effected by heat
sinks?!