Transcript Heat and Wind

Heat and Wind
Heating of Earth (start demo)
•It is radiation from the sun that heats Earth.
•This solar radiation or heat affects both weather and climate.
•Weather is the condition of Earth’s atmosphere at a particular time and
place.
•Climate is the average, year-after-year conditions of temperature,
precipitation, winds, and clouds in an area.
•As we have learned previously, the sun heats different places on earth
at different rates, this unequal heating is due to the tilt of Earth’s axis
causing sunshine to strike Earth at different angles.
•Differences in the amount of heat an area on Earth receives can cause
differences in air pressure.
•Differences in air pressure cause everything from wind to the
movement of hot and cold air masses from one place to another.
Heat and Wind
Convection Currents
Heating
Differences in air pressure
Wind & movement of air masses
• Remember, hot air rises and cool air sinks.
• It is these convection currents in the air that is responsible for moving
air up and down in the atmosphere.
Heat and Wind
Pressure Cells
• When hot air rises from an area, the air pressure decreases, causing
what we call a low pressure cell. (page 399, figure 6)
Low Pressure
High Pressure
• The cold air from another area then rushes into fill the void, creating a
high pressure cell.
Heat and Wind
Air Movement Between Land and Sea
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Land is made of rock, and rock heats up faster than water, so during the
day it is hotter inland than on the coast, but rock also cools off faster than
water, so during the night it is cooler inland than on the coast. (observe
demo)
Since large bodies of water like oceans and big lakes hold their heat and
cool off slowly even at night, a city by the ocean will be warmer at night and
during the winter than inland cities.
Since land heats up faster than water, cities by the ocean will be cooler
during the day and during the summer than inland cities.
Exploring Earth (The Atmosphere in Motion)
Heat and Wind
Wind
• There are two types of wind: local winds and global winds
• Local wind is the movement of cool air known as a sea breeze
rushing into an area of high pressure where hot air has risen to
higher elevations.
• This hot air then moves back to the area where the cool air came
from, creating a convection cell (current).
Heat and Wind
Which one heats up faster, land or water?
Which one cools off faster, land or water?
What is caused by differences in air pressure?
What is responsible for moving air up and down in the atmosphere?
Does cool air create a high pressure or low pressure cell?
Which one is cooler at night, a city at the beach or one that is located inland?