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 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 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. VictoriaWinnipegTimminsSt. John’s Avg. January minimum temperature (°C) Avg. July maximum temperature (°C)

You would expect each of the cities to receive the same 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?!