Download Topic 7 Weather

12-16-14
What is weather?
Do Now:
1. How do you define weather?
2. How do you describe weather?
3. List all possible ways the earth’s atmosphere is heated.
(p.127)
HW – R&H pp. 126-127, A&E #1-7
Weather variables- the details we
use to describe weather.
 Temperature – average kinetic energy of molecules in
air.(thermometer)
 Air pressure- the weight of air pushing down on earth’s
surface (warm air=low pressure)(barometer)
 Wind – horizontal movement of air (blows from high to low
pressure (anemometer)
 Humidity- amt. of water vapor in air (hygrometer)
 Cloud cover- % of sky covered with clouds (eyes)
 Precipitation- rain, sleet, hail, or snow (rain guage)
 Storms- rain, blizzard, tornado, hurricane
12-17-14
What causes wind?
 Do Now: R&H pp. 128-129.
 1. What affect does temperature have on air pressure and
why?
 2. What affect does humidity have on air pressure and why?
 3. As altitude increases, what happens to temperature, air
pressure and air density?
 HW: R&H pp. 131-132, A&E #8-24
Wind- the horizontal movement of
air.
 Caused by uneven heating, causing changes in
temperature.
 Uneven temp. causes changes in air pressure, creating
areas of higher and lower pressure.
 Air or wind blows from regions of high pressure to regions of
low pressure, *always named from where it comes.
 * Can happen locally with land and sea breezes or globally
with wind belts. The greater the pressure gradient the
greater the wind speed. No change in pressure results in no
wind.
Land and Sea Breeze
animation
www.classzone.com/.webloc
12-18-13
What is a wind belt?
 Do Now:
 1. If the barometer is falling what kind of prediction would
you make (temp, humidity, cloud cover, chance of
precipitation)?
 2. What causes wind?
 3. Look at p.129. Use the top right Pressure chart and
convert 30.10 inches to millibars.
 HW- R&H pp. 133-135, A&E# 25-35.
1-5-15
What causes ocean currents?

Do Now: Get out reference tables.

Redraw your wind belt diagram neatly and label all.

1. How does weather travel in the United States?

2. What is the jet stream?

3. Why do deserts form at 30 degrees latitude?

4. What instrument is used to measure wind?

5. What is a pressure gradient?

6. What causes ocean currents?

HW- Finish Castle learning, get weather data.
Ocean Currents
1-6-15
How do clouds form?
 Do Now:
 1. R&H p.138 and describe all the factors that affect
evaporation.
 HW: Get weather readings, Study all weather for quiz
tomorrow!
Humidity Temperature and Dew
Point
1. Humidity – water vapor in the air
 A. Absolute humidity – actually how much water vapor is in
the air in grams/m3
 B. Relative Humidity- the amount of water vapor the air is
holding compared to what it could hold at a specific
temperature, expressed as a %. Warmer air can hold more
water vapor than cool air.
2. Dew Point Temperature- the temp. at which air becomes
saturated or full with water vapor, meaning R.H. is 100%.
Directions on p.139 for determining dew point.
** If air temp. drops below the dew pt. water vapor will have to
condense.
Steps to Cloud Formation
Clouds form
Where moist air
Rises
Expands and
cools.
RAEC- rising air
expands and cools.
Steps to Cloud Formation
1. Rising humid air expands and cools (RAEC)
2. When the air cools to the Dew Point temp. the R.H. will
become 100% meaning air is saturated.
3. Condensation will now occur as long as there is a
condensation nuclei available (ex. Dust, smoke,
pollution) as a surface for condensation to form on. A
cloud is born.
4. Very fine cloud droplets will collide and become larger,
eventually becoming too heavy to be supported by the
cloud and will fall from the sky as precipitation.
Cloud Types
Cumulus- white, puffy, cotton ball,
fair weather clouds.
Stratus – long, thin clouds that
cover large portions of the sky.
Hard to differentiate where one
cloud ends and another one
starts.
Alto- higher up in atmosphere
Cirro/Cirrus Very high up in
atmosphere. Called mare’s tails
and they predict rain is coming.
Nimbo/Nimbus- thunderstorm
version.
1-7-15
How does precipitation form?
 Do Now:
 1. What are the steps to cloud formaton?
 2. What does precipitation do for the atmosphere,
explain?
 HW- Get weather readings, finish lab.
1-9-15
Aim: What is a Station Model?
 Do Now: R&H pp. 152-154.
 1. What is a station model?
 2. How do you indicate wind direction and wind speed on a
station model?
 3. As the difference between the temperature and the dew
point increases at the surface, what happens to the altitude
of the cloud base?
 4. Get weather readings for today.
 HW- Finish lab.
1-12-15
Aim: How do we make a station model?
 Do Now:
 Log on to weather.com and type in 11978 and make a
station model for this morning’s weather. Use R.T. p.13
and R.B. p.153 as a guide.
 Hw. A&E p.142#36-60.
1-13-15
What is an air mass and a front?
 Do Now:
 1. Make a station model of today’s weather.
 2. What types of conditions favor lightning formation?
 HW- A&E p.142#36-60.
 R&H pp.144-146, A&E #61-69
Air Mass- a large parcel of air with similar conditions of
temperature and humidity throughout.
 An air mass takes on the qualities of the location
where it comes from called a source region.
 m-maritime- comes from the water and is humid.
 c-continental- comes from the land and is dry.
 T-tropical- comes from the equator and is warm.
 P-polar- comes from the higher latitudes and is cold.
 A-arctic- comes from the poles and is very cold.
 Pick a lower case and an upper case letter to describe
an air mass based on it’s source region.
Air Mass Source Regions
Front- the leading(front) edge of
an air mass
 Warm front – the leading edge of a warm air mass.
Because warm air is low density it will slowly drift over air
in front of it causing stratus cloud development
Warm Front characteristics
 Warm fronts bring a long period of light precipitation in
front of the front followed by whatever characteristics
the new air mass contains. They are slow moving.
Cold Front- the leading edge of a
cold air mass.
 Because the cold air is high density it moves quickly and
pushes air in front of it up causing cumulus cloud
development and can form a short period of heavy
precipitation on or behind the cold front followed by
whatever conditions the new air mass brings.
Stationary Front
 Where a warm air mass and a cold air mass approach
one another and brings rain for as long as the front stays
in place. Usually the cold air will push the warm air out
of the way eventually moving the front.
1-14-15
What is an occluded front?
 Do Now:
 1. What kind precipitation does a warm front bring and
where would I find it in relationship to the frontal surface?
 2. What is a front and which air mass will always rise
causing possible cloud development and precipitation?
 3. How do winds travel in a low pressure cyclone?
 HW- R&Hpp.147-150, A&E #70-77
Occluded Front- when a cold front catches up to
a warm front in a cyclone and the two combine.
Produces very heavy precipitation.
High and Low Pressure Centers
in the Northern Hemisphere
 Cyclyones- areas of low pressure that are associated
with warmer temperatures, high humidity, and possible
storms. Winds circulate in a counterclockwise and
inward spiral as a result of earth’s rotation. (Lousy
Lows)
 Anticyclones- areas of high pressure associated with
cooler temperatures, low humidity and generally good
weather. Winds circulate in a clockwise and outward
spiral. (Happy Highs)
1-16-15
What is a mid latitude cyclone?
Do Now- 1. List 3 things you can use from a station model to predict and how you would use
them.
2.Describe how an occluded front forms and what kind of weather it brings.
3. Look at p.141, what is the difference between these different types of
precipitation?
HW- Finish lab.
Mid-Latitude Cyclones
 Form as a result of converging cP air from the north and mT
air from the south.
 They start as converging air creating low pressure cyclones.
 Cold fronts catch up to warm fronts and form occuluded
fronts which produce thunder cells.
 The low pressure cyclones spin counter clockwise and
inward and generally move to the northeast in the US.
 These storms can result in thunderstorms, hail storms,
tornadoes, hurricanes or blizzards.
Hurricanes,Tornadoes, Blizzards
 Hurricanes- low pressure cyclones forming in tropical waters
and growing to a massive size. Suck up tremendous amounts
of water and create violent wind (74mph or more), heavy rain
bands, and storm surge waves. Can last for a week or more
and cause the most damage when making landfall. Go to
high ground and under shelter.
 Tornadoes- low pressure cyclones forming from a mid-latitude
cyclone on land. Winds up to 300 mph are concentrated into
a narrow funnel cloud which acts like a vacume cleaner. Last
generally from a minute to an hour. Go underground if
possible.
 Blizzards- a storm with winds of 35 mph or better with
tremendous amounts of snowfall.
1-10-12
Topic 7 Review
 Do Now:
 1. Why is it hot and humid at the equator, whereas it is
hot and dry at 30 deg. North and south?
 2. Use the diagram on the board and make a 1,3, and
5 day prediction for location C.
 HW- Study all of T.7 for exam tomorrow.