Catalyst 1.What makes up the atmosphere?

Agenda Notes – Air Masses (pressure, winds) – Videos – Demo Mini Air Pressure lab

Air Masses I can explain the formation of different air masses.

Air Mass Region of atmosphere with the same temperature, density, air pressure and humidity Can form over water or land Movement of air masses moves over an area, can bring a change in the weather

Air Masses Types: – Continental – air masses that form over land – Maritime – air masses that form over water – Tropical – air masses found near the equator – Polar – air masses found near the poles

Air Masses Tropical maritime – near the equator; over water Warm, moist air Polar maritime – near the pole; over water Cold, moist air Tropical continental – near the equator; over land warm, dry air Polar continental – near the pole; over land Cold, dry air

Air Pressure  Caused by the weight of the atmosphere pressing down on earth  Above each square inch of Earth’s surface is a column of air that weighs 14.7 pounds

Measuring Air Pressure  barometer = instrument used to measure air pressure  Air pressure is measured in millibars  Sea level pressure = millibars

Air pressure can change The higher your altitude, the less air pressure is on you. – This is because there is less air above you

Air Pressure Factors  Cool air is denser – Cool air sinks – This causes pressure to rise (be more)  Hot air is less dense – Hot air rises – This causes pressure to fall (be less)  Humidity = amount of hot water vapor (moisture) in air  Humid air is lighter than dry air  less pressure

Pressure Systems High pressure (H) – cold, dry air that generally brings fair weather (no precipitation or clouds) and light winds Sinking air = high air pressure = clear skies and sunny Low pressure (L) – warm, moist air that generally brings stormy weather with strong winds Rising air = low air pressure = clouds and precipitation

Think… 1.Denver, CO is 5100 ft. above sea level while Warsaw is 154 ft. above sea level. Which would you expect to have higher average temperature? 1.Denver, CO is 5100 ft. above sea level while Warsaw is 154 ft. above sea level. Which would you expect to have higher AIR PRESSURE?

Agenda Notes – Air Masses (pressure, winds) – Videos – Demo Mini Air Pressure lab

Air Density and Pressure Labs In groups of 4 students, rotate through the 5 stations As you are following the directions to complete the lab, make sure you are also answering the questions You will at the end of class have time to finish questions 5 minutes per station… WORK FAST!!

MINI AIR PRESSURE LAB Complete with your table partner!!! Write down all observations and answers to questions in your notebooks » 5 minutes Materials: rubber band, plastic bag, glass jar Procedure: 1.Use the rubber band to TIGHTLY attach a plastic bag over the top of the jar, so that the bag sticks up in the air above the jar. 2.Gently try to push the bag into the jar, without breaking the seal. Observe what happens or what you felt in your notebooks. 3.Remove the bag and rubber band. 4.Next, line the jar with the plastic bag. TIGHTLY attach the bag to the top of the jar with a rubber band. 5.Gently try to pull the bag out of the jar. Observe what happens or what you felt in your notebooks.

Is there air? With your table partner, answer the following questions in complete sentences on a lined piece of paper! You do not need to copy the question down. PREPARE FOR A DISCUSSION. 5 MINUTES 1.Describe what happened when you tried to push the bag into the jar. 2.What happened to the air pressure inside the jar when you pushed on the bag? 3.Describe what happened when you tried to pull the bag out of the jar. 4.What happened to the air pressure inside the jar when you tried to pull the bag out of the jar?

Whiteboards and Discussion

Demo shows the meeting of a warm and cold air mass – show the lack of mixing that occurs when air masses meet in a location on earth The meeting of air masses will often cause severe storms as the two air parcels clash in a location known as the front. Using blue water (cool air) and red water (warm air)

HOMEWORK Go onto the teacher webpage to take notes on winds and fronts Be sure to understand your notes!!

Wind Horizontal movement of air; differences in air pressure – Caused by uneven heating of Earth’s surface Water and land absorb heat differently Wind flows from high air pressure to low air pressure – Gradient = amount of change Larger pressure gradient = stronger winds

Pressure and Wind In which direction would you expect wind to flow?

Winds In Northern Hemisphere: – Winds blow clockwise out of an anticyclone (high) – Winds blow counterclockwise into a cyclone (low) Opposite direction in Southern hemisphere

Winds Cyclone = low-pressure center Anticyclone = high-pressure center

Coriolis Effect Effect of Earth’s rotation on moving objects In the Northern hemisphere, objects moving above Earth’s surface are deflected to the right In the Southern hemisphere, objects are deflected to the left

Coriolis Effect Creates global wind systems that transport colder air to warmer areas and warmer air to colder areas WHY? – balancing the heat energy on Earth

1.Trade Winds – Equator to 30 degrees north and south latitude – Flows East to West towards Equator – How Christopher Columbus got to America…. How boats move between America and Europe; America and Asia GLOBAL WINDS

2. Prevailing Westerlies Flow between degrees N and S latitude Winds move West to East towards the poles. – Responsible for movement of weather in North America (including NC).

3. Polar Easterlies Flows between 60 degrees N and S and the poles. Flow East to West from poles towards the equator

Effects of Global Winds Redistribute heat around Earth Why is this important? Control movement of weather and storms Why is this important? – Ex. Storms in America generally move West to East due to the Prevailing Westerlies

Jet Streams Narrow bands of fast, high-altitude, winds Flow West to East km/h

Front Boundary between 2 air masses – Narrow region separating high or low pressures – Differences in pressure caused by differences in temperature, pressure, and humidity. 4 main types of fronts - cold, warm, stationary, occluded Cold - colder air replaces the warmer air Warm - warmer air replaces the cooler air

Fronts ms/science/weather-and-climate/air-masses- and-fronts.htm ms/science/weather-and-climate/air-masses- and-fronts.htm

Cold Front Cold air pushes warm air and forces it upwards quickly – Warm air rises and condensation happens (CLOUDS) Causes showers and thunderstorms. Squall line = band of high winds and storms associated with a cold front

Warm Front Warm air moves in and replaces a colder air mass Temperature and humidity increase Precipitation (rain, snow, drizzle, etc) found ahead of warm front – Fog common ahead of front

Stationary Front Two air masses meet and neither can move forward Undergo air mass modification so that pressure and temperature of the fronts are similar Very little precipitation

Occluded Fronts Very rapid cold front moves into a warm front – Cold air forces the warm air directly above it Traps the warm air above the cold air. Causes precipitation

Front map 1. cold front 2. warm front 3. stationary front 4. occluded front

How heavy is air? 8sMFw

Demo shows the meeting of a warm and cold air mass – show the lack of mixing that occurs when air masses meet in a location on earth The meeting of air masses will often cause severe storms as the two air parcels clash in a location known as the front. Using blue water (cool air) and red water (warm air)