Download Low - White Plains Public Schools

Let’s try again!
•
•
•
•
Cold air
Humid air
Rainy day
“Nice”weather
High
Low
Low
High
(not necessarily warm!)
•
•
•
•
Snowstorm
July afternoon
North Pole
Equator
Low
Low
High
Low
So, what makes the pressures
different anyway?
Adding water vapor to
atmosphere
&
Heating atmosphere up
Let’s talk about HEAT
Pressure differences are caused
by unequal heating of the Earth’s
surface by the sun.
Why do some things get hot faster?
• Dark colors absorb more sunlight than light colors.
Which gets hot faster: snow or dirt?
• Rough surfaces absorb more than smooth.
Which gets hot faster: ocean water or beach sand?
Equal volumes of the four samples shown below were
placed outside and heated by energy from the Sun’s
rays for 30 minutes.
The surface temperature of which sample increased at
the slowest rate?
(1) Snow
(3) Dark Sand
(2) Copper Pennies
(4) Mud
Which type of land surface will most likely
absorb the greatest amount of incoming
solar radiation?
(1) rough, dark-colored surface
(2) rough, light-colored surface
(3) smooth, dark-colored surface
(4) smooth, light-colored surface
Remember that pressure
differences are caused by
unequal heating of the Earth’s
surface by the sun.
Dark absorbs more…
Rough absorbs more…
Should remain cool
and higher density
?
Should become hot
and lower density
Maybe a dark rough surface?
Air not only rises or sinks, it
also moves naturally from
where there is more (H) to
where there is less (L).
• Ground is heated
sun is…
Thebyeffect
• Atmosphere above ground warms up
• Warmer air becomes less dense and rises
(air current)
• Rising air “gives off” heat energy and cools
• Cooler air becomes more dense and sinks
(air current)
And of course air moves across ground from
High (more air)to Low (less air). (wind!)
The effect can be local or planetary, so let’s examine Earth’s wind…
The cross section shows a sea breeze
blowing from the ocean toward the
land. The air pressure at the land
surface is 1013 mb.
The air pressure at the ocean surface a few miles from the shore is
most likely
(1) 994 mb
(3) 1013 mb
(2) 1005 mb
(4) 1017 mb
current
H
COOL
Convection
cell
WIND
current
L
WARM
• Wind is the result of air pressure differences.
• Pressure difference is better called gradient.
• The larger the pressure gradient, the stronger
the wind.
• Which pressure gradient creates a stronger
wind:
1.8 mb/Km or 7 mb/Km ?
If the distance between these two points is
500 Km, what is the pressure gradient?
The pressure gradient –wind
effect—is not only a localized
effect. It is also a global effect.
Let’s examine the winds of the
Earth...
Does entire planet get equally heated?
Less
heat
High
More
heat
Less
heat
Low
High
Which graph best represents the change
in air pressure as air temperature
increases at Earth’s surface?
H
L
According to the ESRT the
prevailing winds in White Plains,
NY tend to come from the
1) Northeast
3) Southeast
2) Northwest
4) Southwest
http://www.weather.gov/data/obhistory/KHPN.html
After sunrise, a surface wind often develops between the
water and land at the shore. This wind is due to the heat of
the Sun. Which map below best represents the direction of
this wind?