Download Mapping Pressure Systems Objective: Analysis: Questions:

Mapping Pressure Systems
(Source: ​http://www.srh.weather.gov/srh/jetstream/synoptic/surface_press.htm​) Objective:
Predict weather conditions based on the given data.
Procedure:​ ​Using a ​black colored pencil​, lightly draw lines connecting identical values of sea level pressure.
Remember​,​ these lines are called ​isobars​ and do not cross each other.
● Begin drawing from the 1024 millibars station pressure over Salt Lake City, Utah (highlighted in gray).
● Draw a line to the next 1024 value located to the northeast (upper right). Without lifting your pencil draw a
line to the next 1024 value located to the south, then to the one located southwest, finally returning to the
Salt Lake City value.​ Remember​, isobars are smooth lines with few, if any, kinks.
● Repeat the procedure with the next isobar value (1020). Then continue with the remaining values until
you have all the reports connected with an isobar.
Analysis: 1.​ I​ sobars can be used to identify "Highs" and "Lows". The pressure in a “high” is ​greater​ than the surrounding air.
The pressure in a “low” is ​lower​ than the surrounding air.
* Label the center of the high pressure area with a large ​blue​ "H".
* Label the center of the low pressure area with a large ​red​ "L".
2. ​ High pressure regions are usually associated with dry weather because as the air sinks it warms and the
moisture evaporates. Low pressure regions usually bring precipitation because when the air rises it cools and the
water vapor condenses.
* Shade, ​in green​, the state(s) would you expect to see rain or snow.
* Shade, ​in yellow​, the state(s) would you expect to see clear skies.
3. ​ In the northern hemisphere the wind blows clockwise around centers of high pressure. The wind blows
counterclockwise around lows.
Using a ​black colored pencil​...
* Draw arrows around the "H" on your map to indicate the wind direction.
* Draw arrows around the "L" on your map to indicate the wind direction.
Questions:
1. ​What are the weather conditions in…
a​. Salt Lake City (1024 mb):
b.​ Kentucky (1008 mb): 2. ​If the low pressure system moves east, what will weather be like in NJ?
Things to Know:
● Air moves​ from an area of ​high pressure
to an area of low pressure​.
● The warm, low-density, air surrounding
low pressure systems​ moves from left
to right ​(counterclockwise).
● The cold, high-density, air surrounding
high pressure systems​ fall from right to
left ​(clockwise)​ and then moves in to
replace the air rising under the low
pressure system.
● The air around these systems has to do
with the rotation of the Earth and is
known as the ​Coriolis Effect (Figure 1).
● Areas of equal pressure can be connected with lines called i​ sobars​. See ​Figure 2
● Movement of air ​causes surface winds.
Factors related to wind:
● Unequal heating of Earth's
surfaces (absorption of solar
energy by different types of
surfaces)
● Differences in temperature
due to location on Earth
(angle of tilt, incoming solar
radiation)
● Differences in pressure
related to unequal heating
(density of air)
● Direction of Earth's
rotation (​Coriolis Effect​)