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Turn to NB pg. 96
Front and Center
Tuesday, 1/27/15
 Choose your “Golden Line”, a sentence or 2 where
you learned something new about density,
temperature, fronts, weather.
 Mark it somehow with a different color and label.
 Share with your group – student C can start.
 Take turns sharing answers from the 7 questions.
Homework, Due Block Day
In the blank space on NB pg. 106 or on a flappy,
Solve problems #1-4 on TB pg. 421
Show all work. Label all measurements with UNITS
Front and Center –
Questions 1-7
1.
Explain why hot air rises
1.
2.
When air gets warmer, its volume
increases and its density decreases. Air
that is less dense than the surrounding
air will rise.
Explain the difference between
a warm front and a cold front.
1.
A warm front occurs when warm air
overtakes cold air and is gradually
pushed upward.
2.
A cold front occurs when cold air
overtakes warm air and pushes it rapidly
upward.
ChemCatalyst –
discuss w partner
 Large air masses form over different regions of land and
ocean. These air masses have a consistent temperature and
moisture content.
1. What patterns d o you notice in
the tem peratu res and m oistu re
content of the air m asses show n
on the m ap?
2. Why d o you think clou d s form
w hen the Continental Polar air
m ass collid es w ith the Maritim e
Tropical air m ass?
3. Use the concept of d ensity to
explain w hy w arm air in the
Maritim e Tropical air m ass
rises, w hile cold air in the
Continental Polar air m ass
d escend s.
NB pg. 97 (continued)
EQ: How do weather fronts affect weather?
Density, Temperature, and Fronts
 Fronts occur between the boundaries of
warm and cold air masses.
 Warm and cold air masses have different
densities
Warm (tropical) Front
Cold (polar) Front
Warm air overtaking cold air Cold air overtaking warm air
Move up across North
America
Move down across the
continent
Thinner, not as puffy clouds
form days before rain
actually arrive.
Thicker, puffy clouds form
quickly and directly in cold
front area
Ppt come in advance of
front. Steady, light rain.
Ppt occur at or just behind
front. Sudden, heavy
showers.
SWBAT
1/27/15
Front and Center –
Questions 1-7
3. Suppose you have two gas samples in flexible containers
with the same outside pressure and the same amount of gas
in each. Sample A is at a temperature of 25oC and
Sample B is at 5oC. Which of these statements is true?
3.
Sample A occupies a larger volume and has a smaller
density.
4.
Sample A has a greater density and a smaller volume.
5.
Sample B has molecules moving with a greater average
speed.
Front and Center –
Questions 1-7
4.
A cold front is approaching your hometown and is due to arrive
tomorrow. What kind of weather would you expect to observe?
5.
A warm front is approaching your hometown and is due to
arrive tomorrow. What kind of weather would you expect to
observe?
6.
The continental polar air mass overtakes the maritime tropical
air mass.
4.
What kind of front develops?
5.
What happens to the air masses when they meet?
6.
What sort of weather would you expect and where?
 Look in the newspaper or on the internet. Find a recent weather map with at least
one warm front and one cold front.
 Find a warm front on the map. What weather is predicted for
tomorrow in the region of the warm front?
 The temperature will be warmer than on the previous day.
 What weather is predicted in the direction in which the weather
front is moving?
 Cloud weather is predicted ahead of the warm front and a chance of
showers.
 Find a cold front on the map. Describe the weather forecast given
for the region near the cold front.
 Stormy weather is predicted ahead of the cold front.
 What weather is predicted for tomorrow in the region close to the
cold front?
 Stormy weather and decreasing temperatures are predicted as the
cold front passes.
 What weather is predicted in the direction in which the cold front
is moving?
 Warm and humid weather is predicted ahead of the cold front.
 Generally, the weather preceding a
warm front is cloudy with slow and
steady rains and warmer weather as
the front passes through.
 The weather associated with a cold
front is stormy, and the weather
ahead of a cold front in the warm
air mass about to be overtaken will
vary, but should be warmer than the
weather behind the cold front.
 Interactions among the temperature, volume, and density of air
masses contribute significantly to the formation of weather.
 Fronts occur at the boundaries between warm and cold air
masses.
 Warm air, which is less dense, layers over the denser cold air.
SWBAT
 Clouds and steady light rain form ahead of warm fronts.
Clouds and heavy showers form at and behind a cold front.
 On weather maps, Ls are closely associated with fronts while
Hs appear away from the frons. Highs are associated with
clear skies. Lows are associated with storms and cloudy skies.
SWBAT
 Explain the roles of temperature and density in the
movement of cold and warm air masses.
 Describe the weather patterns associated with warm
fronts and cold fronts.
Make the following chart on NB pg.
106 – Title it “Air Pressure Demos”
Demonstration
Balloon in a Bottle
Soft Drink Can
Submerged Cup
Cup and Card
Marshmallows/
balloon
Observations
Explanation
Discussion
1. What observations provide evidence that gases take up space?
2. Provide evidence to support the claim that gases are
compressible?
3. What evidence from the demonstrations shows that air pressure
exists?
4. Describe, in your own words, what you think air pressure is.
Pressure is a force applied over a specific area. Gas
pressure is caused by gas molecules colliding with
objects or the walls of a container.
Discussion Notes (cont.)
 Atmospheric pressure: Air pressure that is
always present on Earth as a result of air
molecules colliding with the surfaces of
objects on the planet. At sea level and 25°C,
there is 14.7 lb/in2 of air pressure from the air
around us. This is referred to as one
atmosphere of pressure, or 1 atm.
Today I Learned or
Confirmed…
Go around in your group and share out one thing you learned
or confirmed today.