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Technology and Weather
Air Pressure
Air Pressure
Earth
The force of air against Earth’s surface
gas particles
gravity
Air pressure and a hot air balloon
faster
farther apart
lowers
low
Hint to help remember…I feel low/sad when it’s cloudy +/or precipitating.
slow down
closer
denser
higherhigh
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
Sea and Land BreezesA 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 DemoLand
heats and cools faster than
water!!
night
day
land
sea
lakes rivers
Global WindsWinds 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 EasterliesWind belts that extend from
the poles to 30° latitude
These winds move cold air from both poles toward the equator.
WesterliesWind belts found between 30° and 60° latitude
Blow towards the poles from west to east carrying moist air over the Unites States
Trade WindsWinds 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.
DoldrumsLocated 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 1What causes winds?
AnswerWinds are caused by the uneven heating of Earth’s surface, which causes pressure differences
Question 2What are the three types of global winds?
AnswerPolar Easterlies
Westerlies
Trade Winds
Question 3What is the difference between a land breeze and a sea breeze?
AnswerSea 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 H H
L L 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 vapor100%
liquidcondenses
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 H H H
L L L L