Chapter 6 Flashcards
Driving force behind wind
Winds are driven by:
The imbalance between equatorial energy surpluses and polar energy deficits
Air Pressure
Air molecules create air pressure through their motion, size and number. this pressure is exerted on all surfaces in contact with air.
Winds are named for the direction from ________
which they originate!
Barometer
Any instrument that measures air pressure
Gravity _______ air, making air denser closer to the Earth’s surface.
compresses
Types of Barometers
Mercury
Aneroid
Density is _____ near Earth’s surface, and ______ with altitude.
Density is higher near Earth’s surface, and decreases with altitude.
Mercury Barometer
- A device that measures air pressure using a column of mercury in a tube
- One end of the tube is sealed, the other end is inserted in an open vessel of mercury
- if the pressure is high the air pressure will push the liquid mercury and the higher the mercury will rise inside that glass tube
Aneroid Barometer
An instrument that measures air pressure without liquid.
A small chamber is partially emptied of air and sealed and connected to a mechanism attached to a needle on a dial.
As the air pressure outside the chamber increases, it presses inward on the chamber, causing changes in the chamber that move the needle.
Normal sea-level pressure
760 mm mercury
- 2 mb (millibars)
- 32 kPa (kiloPascals)
Anemometer
An instrument that measure wind velocity.
Atmospheric/Barometric pressure
Weight of an atmospheric column (body of air above a specified area) as described as force per unit area.
Wind Vane
An instrument that measures wind direction
Wind’s two principal properties
Speed and Direction
Isoline
A line along which there is a constant value
Isobar
An isoline connecting all points of equal atmospheric pressure.
The pattern of isobars provides a portrait of?
the pressure gradient between an area of higher pressure and one of lower pressure
The spacing between isobars indicates?
The intensity of the pressure difference, or pressure gradient.
Why use mercury in a barometer?
Mercury is about 14 times denser than water
Factors Affecting Wind (4)
Gravity
Pressure Gradient Force(PGF)
CoriolisForce (CF)
Friction Force (FF)
Wind
The horizontal motion of air across Earth’s surface.
Wind is produced by…
Differences in air pressure (Density) between one location and another.
Millibar
a measure of force per square metre of a surface area.
High pressure is associated with…
Diverging and descending air
Cold, Dry, Dense air
Low pressure is associated with…
Converging and rising air
Warm, humid, less-dense air