Weather
Learning Goal:
Comprehend and apply weather in
role play of being meteorologists.
El Nino
• El Nino - (El Nee-nyo) is the warming
of water in the Pacific Ocean.
• Rain and flooding along the Pacific Coast
• Warm water disrupts the food chain of
fish, birds, and sea mammals.
• Tornadoes and thunderstorms in the
southern US
• Fewer than normal hurricanes in the
Atlantic
La Nina
• La Nina - (Lah Nee-Nyah) is the cooling of
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water in the Pacific Ocean.
Snow and rain on the west coast
Unusually cold weather in Alaska
Unusually warm weather in the rest of the USA
Drought in the southwest
Higher than normal number of hurricanes in the
Atlantic
• http://esminfo.prenhall.com/science/geoa
nimations/animations/26_NinoNina.html
Water Cycle
• Amount of water remains the same as it
moves through the cycle
• Fresh water is limited
• All living organisms need liquid water
• Earth’s water is continually being
recycled
Evaporation – process by which water
molecules
escape into the air by radiant
energy from the sun changing water into a gas
(water
vapor).
Relative humidity – the percentage of moisture
the air holds relative to the amount it could
hold at a particular temperature.
Psychrometer – instrument used to measure
the amount of R. humidity in the air. It consist of
two thermometers, one wet and one dry.
Cloud formation
Clouds form when water vapor in the air becomes
liquid water or ice crystals. Water vapor
changing into a liquid----CONDENSATION
The temperature at which condensation begins is
called dew point.
Cumulonimbus – Thunderstorm clouds that
produce severe weather, tornadoes, hail, strong
winds. Have anvil shape to top of cloud.
Clouds
Cumulus – usually indicate fair weather. 2 to 7
miles in the sky (cotton balls).
Cirrus – Feathery or fibrous in appearance. Very
high altitudes usually between 6 and 12
kilometers. Indicate the onset of rain or snow in
a few hours.
Stratus clouds – smooth gray clouds that cover
the whole sky and block out the sun are
called stratus clouds. These clouds produce
steady, light precipitation.
Precipitation – Water vapor that condenses and
forms clouds that can fall to the Earth as rain,
sleet, snow, freezing rain or hail.
sleet – water droplet that freezes when it
falls through cold air. (winter)
snow – forms when water vapor changes
directly to a solid.
Hail – ice balls that fall after water is frozen
in the air then pushed further up and
collects more water and freezes again, over
and over until it becomes to heavy to stay
suspended in the air. The stronger the uplift
the larger the hail stone. (summer)
Freezing rain – rain that freezes upon contact
with the ground.
Isobar
A line on a weather map connecting places
that have the same air pressure
high-pressure system
A generally calm and clear weather
system that occurs when air sinks down in
a high-pressure center and spreads out
toward areas of lower pressure as it nears
the ground.
(More dense cold air)
low-pressure system
A large and often stormy weather system
that occurs when air moves around and
into to a low-pressure center, then moves
up to higher altitudes.
(Less Dense Warm Air)
http://www.bom.gov.au/lam/Students_Teac
hers/pressure.shtml
Storms
• Caused by:
• Changes in temperature & drop in barometric
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pressure
Ex: Hurricanes are a low pressure mass over
tropical (warm) water
http://news.bbc.co.uk/2/hi/5328524.stm
http://profhorn.meteor.wisc.edu/wxwise/tornado
/t.html
http://www.suu.edu/faculty/colberg/Hazards/Hu
rricanes_Noreasters/Hurricanes_Anim_1.html
Weather Fronts
• Air mass-a huge body of air that has
similar temperature, humidity, and air
pressure
• Front-the area where two air masses meet
and do not mix
• Dense,cold air moves underneath the less
dense warm air, pushing it up
Front Types
• Cold front-rapidly moving cold air mass
that runs into a slowly moving warm air
mass
• Move quickly, causing violent storms
• Warm front- warm air that collides with
cold air
• Moves slowly, causing fog or rain for days,
and in the winter, snow
Cold Front
(More Dense cold Air)
Cold Front
Warm Front
(Less Dense Warm Air)
Warm Front
Stationary Front
• http://www.stevemcentee.com/animation3
.html
Stationary Front
Weather Forecasting
• Meteorologists-scientists who study
weather and try to predict it
• Forecasting has greatly improved due to
computer technology
• Collecting weather data has improved
because of satellites and balloons
Seasons and Climate
• Earth has seasons because Earth’s axis
tilted as it moves around the sun
• Winter-axis tilted away from sun resulting
in shorter days and indirect rays
• Summer-axis tilted toward sun resulting in
longer days and direct rays
Climate
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Caused by:
Altitude
Latitude
Mountain barriers
Proximity (closeness) to oceans
• Climate is classified by precipitation and
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temperature based on these factors
http://www.edheads.org/activities/weather/inde
x.shtml