1. Aim: How does atmospheric pressure predict the weather?

2. Explain the lyrics to this song. How do you know pressure exists?

3. How do we define atmospheric pressure?
Atmospheric pressure (air pressure)– the weight or force of the air pushing down on a unit area of surface.
Atmospheric Pressure Weight is a force. Air has weight. If you hold a book in the palm of your hand, you will feel the weight of the book pressing down. The amount of force pushing down on a unit area of surface is called pressure. When you hold the book in the palm of your hand, the book’s weight is spread over your entire hand. A force exerted over a small area causes more pressure than the same force applied over a large area.

4. How does altitude affect atmospheric pressure?
Altitude (elevation): Altitude increases, pressure decreases
Pressure
Altitude

5. How does temperature and moisture affect atmospheric pressure?
Why are the rooms different sizes?
Which room would weigh more and why?
Which temperature air mass(room) would have more air pressure? Explain.
Low Pressure = Warm Temperature & moist air (humid)
High Pressure = Cold temperature & low moisture (dry air)
Pressure
Moisture
Pressure
Temperature
As Temp increases = Pressure decreases
As Moisture increases = Pressure decreases
Air molecule weighs 58 grams
Moisture molecule weighs 50 grams

6. How atmospheric pressure is measured?
Barometer - instrument used to measure pressure. Measure in millibars (mb) or inches of mercury (Hg)
At sea level, Standard air pressure = one atmosphere
29.92 inches of mercury or millibars.
How atmospheric pressure is measured?
Falling barometer – Low Pressure
Bad Weather (rain), Storm
Rising barometer – High pressure
Good Weather (sunny)

7. How do we convert between inches of mercury and mb?
Convert the Pressures Below:
Millibars (mb)
Inches of Hg (in) mb
30.15 inches
978 mb
28.88 inches
1019 mb
30.09 inches mb
29.73 inches
millibars (29.92 inches)

8. Answer the questions on the worksheet
Summary Activity
Answer the questions on the worksheet
As the temperature of the atmosphere at a given location increases, the air pressure will most likely
(1) decrease (2) increase (3) remain the same
2. On a July afternoon in Florida, the barometric pressure is inches and falling. This reading most likely indicates
(1) rapidly clearing skies (3) gradually improving conditions
(2) continuing fair weather (4) an approaching storm
3. A high-pressure center is generally characterized by
(1) warm, dry weather (2) cool, wet weather
(3) cool, dry weather (4) warm, wet weather

9. Extra Questions