Technology and Weather

Air Pressure Think Back… What does an increase in temperature do to particles?? An increase in temperature makes particles speed up, bounce off each other, and expand.

Air Pressure Air pressure is: The force of air against Earth’s surface It is caused by _____ ____________ in the air Pushing against each other and against the _____________, due to the force of ______________. The force of air against Earth’s surface gas particles Earth gravity Air pressure and a hot air balloon

When air is heated, its molecules move ______ and __________ ________. The air becomes less dense and air pressure _______. A region with low pressure is called a ___________. faster farther apart lowers low Hint to help remember…I feel low/sad when it’s cloudy +/or precipitating.

As air cools, the molecules ______ _______, and move ________ together. The air becomes ___________ and has a __________ pressure. A region with high pressure is called a ___________. slow down closer denser higher high Hint for remembering: I’m Happy when skies are clear and fair.

Think back to convection currents. Why do warm molecules rise and cooler molecules sink? Warm molecules are less dense so they rise up. As they rise up, they cool, become more dense, and therefore sink.

So what is wind??? Wind Song The reasoning of less dense molecules rising helps explain how wind is formed. Like other gases, air moves from a region of _______ density to a region of _______ density. Cold, _____ _________ moves in to replace the warmer, rising air. The air moving from high to low pressure areas is called ______. higher lower high pressure wind

Sea Breeze

Land Breeze

Land heats and cools faster than water!! Sea and Land Breezes A land breeze occurs during the ______; a water (sea) breeze occurs during the _______. Air flows from land to water in a ________ breeze; air flows from water to land in a ______ breeze. Land and water breezes can be found on the shores of large _________ and _________, as well as along seacoasts/oceans. Sea and Land Breezes Demo night day land sea lakes rivers Land heats and cools faster than water!!

Global Winds Winds that blow across long distances in predictable patterns. They carry air masses from one region to another. Each winds always blows in the same direction. Global winds do not flow straight, they curve because Earth is rotating. coriolis effect http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm Global Winds in the United States (prevailing westerlies) move weather from the West to the East

Polar Easterlies Wind belts that extend from the poles to 30° latitude These winds move cold air from both poles toward the equator.

Westerlies Wind belts found between 30° and 60° latitude Blow towards the poles from west to east carrying moist air over the Unites States

Trade Winds Winds that blow from 30° almost to the equator Warm air from the equator moves at high altitudes over oceans. There it cools, descends, and begins to flow back toward the equator.

Doldrums Located along the equator where no winds blow because the warm rising air creates an area of low pressure. As air rises and cools near the equator, water vapor condenses causing it to rain almost everyday near the equator.

Global Winds

Question 1 What causes winds?

Answer Winds are caused by the uneven heating of Earth’s surface, which causes pressure differences

Question 2 What are the three types of global winds?

Answer Polar Easterlies Westerlies Trade Winds

Question 3 What is the difference between a land breeze and a sea breeze?

Answer Sea breezes occur during the day when the land is warmer than water and a land breeze occurs at night when the water is warmer than land

Weather Game… Temperature Air Pressure Density H L

Temperature and Humidity Water evaporates when it changes from a _____to a _____. Humidity is moisture in the air in the form of a gas called ______ ______. Water vapor comes from any source from which water ________ into the air. liquid gas water vapor evaporates

When the air has more water vapor that at other times we say it is more ________. The amount of water vapor that air can hold depends on the air ___________. The warmer the temperature, the _____ water vapor the air can hold. The cooler the temperature, the ______ water vapor the air can hold. ___________ _________ is what meteorologists refer to when reporting the amount of ________ _________ in the air. At _______ humidity the air can not hold any more water vapor, and water returns to its _________ form. The temperature at which water vapor ___________ is called a dew point. humid temperature more less Relative humidity water vapor 100% liquid condenses

Why do you feel more comfortable on a hot, dry day than on a hot, humid day? On a hot dry day there is less humidity and less water vapor in the air. High levels of water vapor in the air (highly saturated air) doesn’t have more room for water to go into it and it feels sticky to your skin.

Weather Game… Temperature Humidity Density Air Pressure H L