Chapter 16 - Understanding Weather
http://youtu.be/3xcSpOnabkU
1 ½ min weather song – Bill Nye
http://youtu.be/UtgFHHhm1xU
3 min What is weather? NASA
Weather Conditions
•Weather is the condition of the atmosphere at a
particular time and place.
•Scientists collect data to predict weather:
•Temperature
•Precipitation (rain, snow, sleet or hail)
•Humidity (amount of water vapor in the air)
•Air pressure (low or high)
•Wind direction
Meteorology – study of the atmosphere changes in temperature, air pressure,
moisture, and wind direction in the
troposphere.
Weather Instruments
•Barometer – measure air pressure
•High – fair weather
•Low – stormy weather
•Thermometer – measures
temperature
•Anemometer – measures wind speed
Humidity
•Humidity is the amount of water vapor in the atmosphere.
•High humidity contains a large amount of water vapor.
Air pressure
•Air pressure is the weight
applied by a column of air above
a certain location on Earth’s
surface.
•Warm air is less dense so it
exerts less pressure.
http://youtu.be/jmQ8FWnM0fA
4 ½ min air pressure
Global Winds
•Global winds move high pressure air and low
pressure air across the Earth’s surface.
•As the air masses move into an area, it
changes the weather – the condition of the
atmosphere.
•Jet stream
•Prevailing Westerlies
http://youtu.be/CgMWwx7Cll4
4 min The Jet Stream and Weather
http://youtu.be/kvk-hBFnBTI
4 1/2 min What are air masses?
Low-Pressure System
•A large mass of air with low pressure is called a low-pressure
system, or a low.
•A low usually brings rainy weather, a possible hurricane,
thunderstorm or a tornado.
High-Pressure System
•A large mass of air with high pressure is called a highpressure system, or a high.
•A high usually brings clear (fair) weather.
Fronts
http://youtu.be/vPC5i6w3yDI
3 min weather fronts
http://youtu.be/1ltM3GYNmtQ
4 min BBC Battle of the Weather Fronts
http://youtu.be/G7Ewqm0YHUI
5 ½ min What are weather fronts?
•A front is an area in which two types of air masses meet.
•Four types – cold, warm, stationary & occluded
COLD FRONT
•Cold air forces its way under warmer air
•Creates violent storms
•Pass quickly
WARM FRONT
•Warm air slides up and over cooler air
•Brings a steady drizzle of rain
•Stays around for a day or two
STATIONARY FRONT
•Air masses (cool & warm) have run out of energy and
have become similar or equalized.
•A little bit of wind but a lot of rain for several days.
OCCLUDED FRONT
•Troublesome
•Combine the worst of warm and cold fronts
•Warm front has been overtaken by a cold front
and the warm air is forced upward.
•High winds from cold fronts
•Steady rains from warm fronts
Hurricanes
•Large, rotating, LOW AIR
PRESSURE weather system
that forms over the warm
ocean waters near the
equator.
•Occur from summer through
fall due to the oceans heating
up.
•Similar storms that form over
the Indian & Pacific Oceans are
called cyclones.
http://www.youtube.com/watch?v=xWUegShRWs0&feature=share&list
=PLjzOc3wmoa1i-8SzFQup3po5S4mtRPiFW
4 min What is a hurricane?
Hurricanes
http://youtu.be/Cdh853PdVb0
4 min Hurricanes
http://youtu.be/zP4rgvu4xDE
***3 min Hurricanes
•Begins as a low air pressure system – tropical storm or depression
•Over warm, Atlantic Ocean water near Africa
•Winds push it towards the east coast of the USA
•Gains energy from the warm, humid air just above the water
•Increases wind speed and rotation
•At wind speed of 75+ mph, it becomes a hurricane.
Hurricanes – when they reach land
•Bring heavy rains and strong winds
•Winds blow seawater toward land
•The rise in water as it moves inland is called a storm surge.
•Storm surges causes the most damage - flooding in the coastal areas
http://youtu.be/iOw6ONcKk4g
3 ½ min. Hurricanes & Twisters song Mr. Parr
Hurricanes
•A hurricane weakens as it
moves inland or makes
landfall.
•WHY? Without the heat
energy from the ocean, it
loses energy quickly.
•A huge weather storm that
can last for days and even
weeks.
THUNDERSTORMS
http://youtu.be/exlVSEPEXKc
1 min thunderstorm formation
http://youtu.be/NxWbR60tFlg
1 ½ min The Thunderstorm Recipe
•LOW AIR PRESSURE weather system
•Heavy rainstorm that includes lightning as well as thunder
•Form when there is unstable air and moisture
•Common on hot, humid days, especially on summer afternoons
•Small compared to hurricanes, but can be deadly.
•Short-lived
http://youtu.be/7nZlGg59MRw
3 ½ min Thunderstorm song Mr. Parr
THUNDERSTORMS
•Winds inside the
thunderstorm cause
electrical charges to
build up.
•When charges move
from cloud to cloud, or
to ground, this is called
lightning.
•Lightning heats the air,
causing the air to
expand.
•Which causes a shock
wave or thunder.
http://youtu.be/RDDfkKEa2ls
2 min upward lightning
http://youtu.be/RLWIBrweSU8
3 min lightning
http://youtu.be/jM8h60S1GsM
2 min explains lightning
THUNDERSTORMS
•The SUN heats the
Earth’s surface.
•The surface heats the
air above it.
•This produces
convection currents –
warm air rises and cool
air comes (sinks) in to
replace it.
•Tall clouds called
thunderheads are
formed.
http://youtu.be/ur0k7UDrrvg
4 min cloud types with music
CLOUDS
•A cloud is a collection of millions of tiny water droplets.
Remember the WATER CYCLE –
HEAT (Sun)
EVAPORATION
water vapor
cool air
CONDENSATION water droplets
cloud formation
PRECIPITATION (rain, snow, sleet or hail)
Precipitation
•Precipitation is any form of water falling to Earth –
rain, sleet, snow or hail.
•Rain is the most common form.
•Sleet starts out as rain and then freezes.
•Snow forms from a gas (water vapor) into a solid.
•Hail is very damaging because it is balls of ice.
CLOUDS - Cumulus
•Puffy, white clouds with flat bottoms
•Sign of fair/pleasant weather
•A thunderstorm comes from a
cumulonimbus cloud.
CLOUDS - Stratus
•Form in layers
•Cover large areas
•Often blocks out the sunlight
•Fog – a cloud that forms near the ground.
http://youtu.be/K-XSkbPJgEQ
4 min What is fog?
CLOUDS - Cirrus
•Thin, feathery white clouds
•Found at high altitudes
•Made of ice crystals
•If cirrus clouds get thicker – change in weather
CLOUDS - Prefixes and Suffixes
•-Nimbus
• Nimbo-
produces precipitation
• Cirro-
located in the high altitudes
• Alto-
middle altitudes
TORNADOES
•A tornado is a highspeed, spinning (rotating)
column of air
•It is a LOW AIR
PRESSURE weather
system.
•Tornadoes produces
Earth’s most powerful
winds.
•Small compared to
hurricanes but still deadly
•Short-lived
http://youtu.be/MRykm-xjPsk
1 min The Anatomy of a tornado
http://youtu.be/006guBgSf14
2 ½ min Actual footage of a forming
tornado
http://youtu.be/_5TiTfuvotc
2 min Safety
TORNADOES
•Begins as a funnel-shaped cloud that is rotating.
•When the funnel cloud touches the Earth’s surface, it picks
up dust and debris.
•The flying debris causes the most damage to property
and buildings, and to the people inside the buildings.
http://youtu.be/WvRv-243Cmk
75 minutes of rain and thunder – relaxing
http://youtu.be/7nZlGg59MRw
3 ½ min. Thunderstorm Song Mr. Parr
http://youtu.be/8PjIGBW-unc
3 ½ min. Flood Song Mr. Parr
http://youtu.be/u-ipJLjiIcc
3 ½ min. Storm Clouds Song Mr. Parr
http://youtu.be/LD4hSW2mys0
3 min Weather Fronts Song Mr. Parr
http://youtu.be/kBfaAN_tWW4
3 ½ min Weather Instruments song Parr
Chapter 16 - Understanding Weather
PowerPoint Presentation
Created by M. Brumbaugh
TCMS - 2013