the diagram shows weather instruments a and b. which table correctly indicates the name of the...
TRANSCRIPT
The diagram shows weather instruments A and B.
Which table correctly indicates the name of the weather instrument and the weather variable that it measures?
Weather?
LOW pressure air• Less dense
• Weighs less
• Tends to rise
• Warm
• Wet
• Lousy weather (rainy, snowy, etc…)
L101210081004
HIGH pressure air• More dense
• Weighs more
• Tends to sink
• Cool
• Dry
• Nice weather (sunny, blue sky, etc…)
H100410081012
In late October cool
weather is relatively H pressure. Watch the L pressure storm develop:
LOW PRESSURE means...
Warmer
More Humid
Is HIGH or LOW pressure normal?
At the Equator?
On a sunny day?
On a winter day?
On a rainy day?
At the North Pole?
Low
High
High
Low
High
Two reasons why air becomes HIGH or LOW pressure :
1. Unequal heating of Earth’s surface.
2. Change in humidity.--we will discuss water vapor later--
Why would the sun make the ground
hot in one place and not as hot in another place?
ColorTextureSpecific Heat…
At pressure centers…
• Different surfaces absorb different amounts of energy (color, texture, specific heat, etc…)
• Different surfaces absorb different amounts of energy (color, texture, specific heat, etc…)
• Low density air is created above warm surface.
At pressure centers…
• Different surfaces absorb different amounts of energy (color, texture, specific heat, etc…)
• Low density air is created above warmer surface.
• Density change causes air to move…
At pressure centers…
Then things get
interesting!
Which transfer of energy occurs mainly throughthe process of convection?
(1) electromagnetic energy transferred from the Sun to the Moon
(2) solar energy transferred through space to Earth’s surface
(3) heated air in the lower atmosphere transferred upward by density differences
(4) heat from radioactive decay transferred by molecular collisions to surrounding mantle rock
Air pressure decreases as air
heats above a warm Earth surface.
Warm, LOW
Density Air
Cold, HIGH
Density Air
Low density air wants to float!
As HIGH pressure air sinks, it hits surface and
diverges (spreads out).
As LOW pressure air
rises, more air converges
(comes together) to fill empty
space.
It’s a CONVECTION
CURRENT
H LAir moving horizontally from higher to lower pressure is
WIND.
H LAir moving horizontally from higher to lower pressure is
WIND.
Air moves like water...
Big gradient = Fast
Small gradient = Slow
The larger the AIR PRESSURE GRADIENT, the faster the wind moves
from HIGH to LOW pressure!
The larger the pressure
gradient, the faster the wind!
Which location most likely recorded the highest wind
speed?
(1)A (3)C
(2)B (4)D
The map at left shows pressure
measured in mb. The distance between the
points is 500 Km. CALCULATE the
pressure gradient.
Gradient = Change in field value/ distance
Gradient = 1004 mb – 976 mb/ 500 Km = 28 mb/ 500 Km
Gradient = 0.056 mb/ Km