Ch. 10.2 Water’s Influence on Weather and Climate

How Water Moderates Air Temperature

• Timmins, Ontario and Victoria, British Columbia are each located along the 48th line of latitude

• Timmins’ average temperature ranges from 17°C in July to -18°C in January; Victoria’s average temperature ranges from 16°C in July to 5°C in January

• Why such a difference in Winter temperatures?

Victoria

Timmins

How Water Moderates Air Temperature• the main reason for this is that Victoria sits

next to an enormous body of water (the Pacific Ocean), while Timmins is far from any ocean or big lake

• this is because water takes longer to cool/heat than air

• large bodies of water keep nearby regions from experiencing very high temperatures in the summer and very low temperatures in the winter

How Water Moderates Air Temperature

• heat capacity – the ability of a material to absorb heat– when measuring a material’s heat capacity,

scientists measure how long the material takes to heat up (absorb heat) and cool down (release heat)

– a material with high heat capacity takes longer to heat up and cool down than a material with lower heat capacity

How Water Moderates Air Temperature

• water has a higher heat capacity than either air or land

• when the land and air has cooled off in the winter, the water is still warmer and giving off heat to the air around Victoria

• when the land and air are hot in the summer, the water is still colder and is cooling the air around Victoria

Moderation in Action

daytime and Summer

nighttime and Winter

Water Bodies and Regional Climates

• large water bodies are major contributors to climate differences experienced from region to region

• these large water bodies moderate the temperatures nearby in both summer and winter

• they also provide large amounts of moisture to the air

Microclimates

• microclimate – area with a small localized climate variation that differs from the larger climate area around it– greenhouses artificially create microclimates– Has anyone ever noticed the difference in climate

between the northern part of St. Kitts and the southern peninsula?• discuss

MicroclimatesLake-effect snowfall creates microclimates around the Great Lakes

Water Bodies and Global Climate

Northern Hemisphere: 39% Land, 61% ocean annual average temperature varies 14.3°C

Southern Hemisphere: 19% Land, 81% ocean annual average temperature varies 7.3°C

Coastal Storms• Living in St. Kitts and Nevis, we are all familiar

with tropical depressions, tropical storms, and hurricanes.

• It is the presence of the warm bodies of water (like the equatorial Atlantic, Caribbean Sea, and the Gulf of Mexico) that allow these storms to form.

• Regions far from these warm bodies of water don’t need to fear these storms.