Warm up  Your warm up is at your desk  Remember, warm up time is a time to be quiet (below the music), be seated, and working  Phones need to be away when the bell rings

Review  1. Which layer of earth’s atmosphere has the most air pressure?  2. Pressure on the top of a mountain is (less, more ) than at sea level?  3. What instrument do meteorologists use to measure pressure?  4. What units are used to measure pressure?  5. Air moves from __________pressure to___________pressure.  6. Air moves___________________around high pressure and air moves ______________________around low pressure.  7. Warm air rises and cold air sinks because of differences in ____________.

Wind  Wind caused by changes in air pressure  Air pressure changes caused by uneven heating of the atmosphere  Winds measured by direction (from where it comes) and speed (miles per hour) using an anemometer  Wind chill is increased cooling caused by wind in the winter

Local, daily (diurnal) breezes  Local daily (also called diurnal) breezes include:  Land and sea breezes  Mountain and valley breezes

Sea and Land  Caused by : Differential heating of land and sea

Sea Breezes (named for where the wind blows from)  Sea Breeze blows from the ocean toward the land  Explanation for sea breeze: during the day, the sun heats both the land and sea. Land heats up quicker during the day than the water. This causes the air over the land to be warmer and to rise (lower pressure). Over the ocean, the air is cooler during the day and it sinks (higher pressure). Wind will blow from the ocean to land (from high to low).

Land Breeze (named for where the wind blows from)  Land Breeze blows from the land toward the ocean.  Explanation for land breeze: At night, the water is now warmer than the land. Water takes longer to cool down than land. Now, air is warmer over the ocean and rises (low pressure). Meanwhile air over the land is colder and sinks (high pressure). Wind will blow from the land to the ocean (high to low)

Mountain and Valley breezes

Valley and mountain breezes explained  Valley breezes: During the day, the mountain side is directly heated by the sun. Air in the valley is cooler and so it sinks (high pressure). Since air moves from high pressure to low pressure, the air moves from the valley up the mountain side. Water vapor is brought with the air which condenses as clouds at the peaks of mountains.  Mountain breezes: At night, the mountain side cools down very quickly due to altitude. This creates high pressure on the mountain side and air flows down the mountain into the valley. Water condenses in the valleys and is seen in the morning as fog.

Closure  Create 2 venn diagrams. Worth 10 points!  1. Sea breeze vs land breeze  2. mountain breeze vs land breeze

The Coriolis effect Is a result of Earth’s rotation Causes moving objects to follow curved paths: In Northern Hemisphere, curvature is to right In Southern Hemisphere, curvature is to left Changes with latitude: No Coriolis effect at Equator Maximum Coriolis effect at poles

The Coriolis effect on Earth As Earth rotates, different latitudes travel at different speeds The change in speed with latitude causes the Coriolis effect Figure 6-9a

Missile paths demonstrate the Coriolis effect Two missiles are fired toward a target in the Northern Hemisphere Both missiles curve to the right Figure 6-9b

Coriolis effect influences air movement Northern Hemisphere winds curve to the right as they move from high to low pressure Causes wind to circulate: Clockwise around high-pressure regions Counterclockwise around low- pressure regions Figure 6-12

Pressure Belts  As warm air rises at the equator and moves toward the poles, it cools  As it cools, some of the air sinks around 30° north and south of the equator

Pressure Belts  At the poles, cold air sinks and moves towards the equator  Around 60° north and south, the air begins to heat up and rise

Global Convection cells

Global Winds  The combination of pressure belts and the Coriolis Effect cause global winds  These are polar easterlies, prevailing westerlies, and trade winds

Polar Easterlies  Wind belts that extend from the poles to 60° latitude  Formed from cold sinking air moving from the poles creating cold temperatures

Prevailing Westerlies  Wind belts found between 30° and 60° latitude  Flow towards the poles from west to east carrying moist air over the United States

Trade Winds  Winds that blow from 30° almost to the equator  Called the trade winds because of their use by early sailors

Doldrums also called the intertropical convergence zone (ITCZ)  Located along the equator where no winds blow because the warm rising air creates and area of low pressure

Horse Latitudes  Occur at about 30° north and south of the equator where the winds are very weak  Most deserts on the Earth are located here because of the dry air

Jet Stream  The jet streams are narrow belts of high speed winds that blow in the upper troposphere and lower stratosphere  Separates warm air from cold air