Ms. Longo Earth Science Weather & Water

10-26

Announcements Bring a book for SSR tomorrow No school Friday No Saturday school this week

Do Now Response Sheet-Investigation 3 Put your name on the BACK of the page Answer the questions on Notebook sheet 6 You have 10 minutes to answer Sheets will be collected

Agenda Barometers Weather Balloon Simulation Vocabulary

Barometer Images Examples of barometers The prefix baro- means pressure The suffix –meter means measure Air pressure can be measured in inches (of mercury) or bars. A bar is equal to the pressure exerted by the air in the atmosphere at sea level. The millibar (mb) is equal to 1/1000 of a bar and is usually used to measure atmospheric pressure. Average sea-level air pressure is 1013 mb

Barometers Barometer in a Bottle video Look at the picture What can we do to change the pressure reading on the barometer in the jar?

Barometer in a Bottle video Why do you think the pressure reading changed? What could we do to decrease the air pressure reading?

Weather Balloon Simulation Notice how air pressure changes as altitude increases. Look for changes in air density in the box on the right The amount of the atmosphere’s mass below the elevator is listed in the bottom right corner

Vocabulary Bar: the unit of measurement for air pressure. A bar is equal to the pressure exerted by the air in the atmosphere at sea level. Millibar: (mb) the unit that meteorologists use when reporting air pressures on a weather map; equal to 1/1000 of a bar Density: the amount of mass in a material compared to its volume Equilibrium: when air moves from an area of high pressure to one of low pressure, making the air density equal

10-27

Do Now: Get out your notebook FQ 3.1 How does pressure affect air? Answer the question now You have 5 minutes to do this Get out a pencil for today’s activity

Agenda FQ 3.1 FQ 3.2 Air Pressure maps

Focus Question 3.1 Share your answers with your table group and add more to your answer if necessary You have 4 minutes to do this

Discussion Think about this: We have discussed equilibrium. If air in a container is under higher pressure than the surrounding air, when the container is opened, air will flow out until there is equilibrium, so all the air is at the same density and pressure. What happens in nature when air can flow freely, and is not held in containers?

FQ 3.2 What happens when two areas of air have different pressures? Please write the Focus Question in your notebook Do not answer now

Air Pressure map The numbers on this map represent barometric pressure data collected at weather stations across the United States. The weather stations report their data to the National Weather Service to create maps like this. The numbers represent millibars of atmospheric pressure. Meteorologists use atmospheric data such as these to analyze and predict the weather. We are going to use these data to predict the wind.

Notebook sheet 7 We are going to connect the air pressure data with lines called isobars. The isobars connect areas of similar pressure to show us areas that have the same pressure. Isobars are smooth lines and cannot cross each other. You will need a pencil for the activity

Notebook sheet 7 We will begin with the areas of lowest pressure. Which stations have the lowest millibars pressure? Plan where you will draw first Draw a line from one ______ mb station To the next ______mb station and continue to the next without lifting your pencil.

Notebook sheet 7 Pressure everywhere around the 1004 line will be 1004 mb. Find the area of highest pressure, 1024 mb. Connect the areas of 1024 mb pressure Notice that the difference in pressure between isobars is 4 mb.

Notebook sheet 7 What is the next lowest reading from a weather station? _______ mb Look at the example, then draw a circle connecting the _____ mb areas

Notebook sheet 7 We can’t cross other isobar lines, and the 1020 mb line separates the map into east & west. We will connect the 1016 stations in the east together into a loop. We will connect the western stations with a line, because we can’t cross other isobar lines.

Notebook sheet 7 We will repeat the process for the 1012 mb stations Make a circle in the east, and a line in the west. Try to connect the 1008 stations on your own.

Notebook sheet 7 Label the Isobars The letters H and L on the map show where the air pressure is highest and lowest in a region. The numbers on the isobars moving away from an H get smaller, and numbers on the isobars moving away from an L get larger. Mark the H and L on your map

Surface Air Pressure Map with Isobars Check your work and make any necessary corrections Color the H blue, and the L red

Discussion Be prepared to answer the questions Look at your diagrams Will wind go from high to low pressure areas or from low to high pressure areas? Explain your answer using evidence from class experiments with syringes