Transcript Weather maps

►Weather forecasting dates back to 650 B.C. The
Babylonians observed cloud patterns to predict
weather.
►Aristotle described weather
patterns in Meteorologica
around 350 B.C.
►Forecasting was
based on simple
scientific observation.
Example - if sunset
was red then fair
weather was predicted
for the following day
“Red sky at night, sailor’s
delight…red sky at
morning, sailor’s
warning”
►During the Renaissance weather forecasting
improved.
►Galileo Galilei invented the thermometer in the
16th century.
Temperature
►Evangelista Torricelli invented the mercury
barometer in the 17th century.
Air Pressure
These instruments enabled quantitative observation a giant leap toward modern meteorology, the
scientific study of Earth’s atmosphere.
►1820, the German astronomer and meteorologist
Heinrich Wilhelm Brandes published the world’s first
weather charts.
►The invention of the electric telegraph in 1835 was
when the modern age of weather forecasting began.
The telegraph allowed reports of weather conditions
from a wide area to be received almost
instantaneously.
Modern Weather Forecasting:
Technology and Precision
Radar, satellites and computers have been used
regularly in weather forecasting since the late 20th
century.
There are 5 basic types of
maps:
1.Pressure
2.Aviation
3.Temperature
4.Streamline
5.Station Model
►Tells the air pressure
►Gives the locations of high-pressure areas and lowpressure areas
Low Pressure and Bad Weather
Air warmed by the sun on the earth's surface can hold more
moisture than cool air. As the warm moist air rises, it begins to
cool. Eventually, the air reaches a level where it is too cool to
continue to hold its moisture. At this point the moisture
condenses out to become clouds. The clouds release their
water as precipitation.
High Pressure and Clear Weather
High pressure areas are produced by cooler, heavier, sinking air.
This air contains less moisture and is more stable. In the
summer, high pressure usually means sustained sunshine, few
clouds, low winds, high temperatures, and dry weather. In
winter, the lack of cloud cover can cause the temperatures to
be very cold, since the lack of clouds allows heat from the
earth to travel away from the earth.
Tells information necessary for safe flight of aircraft:
►Wind speed and direction
►Dew point
►Cold and warm fronts
►Icing areas
►Flight restriction information
Shows temperature either in color-coded format
or with the actual numbers.
Shows wind patterns
Shows the weather conditions at a particular
weather station (a place where weather is measured
and recorded)
Several conditions are measured:
►Temperature
►Humidity
►Air pressure
►Cloud cover
►Wind speed
►Wind direction
Symbols are used
What information is this station
model giving?
Temp - 81°
Dew Point – 59°
Air Pressure - 221
Winds 15 mph from the NE
Cloud Cover – 75%
How fast is this wind
blowing..AND in what
direction?
65 mph from the
Northwest
Using the Symbol Key from the next slide…fill in this
chart at your seat, then we ca
Humidity refers to the amount of moisture
(water vapor) in the surrounding air.

RATIO of the amount of moisture in the air
compared with the amount of moisture the air can
hold at that temperature and pressure.

Expressed as a percentage.

If the air is at 90%
relative humidity,
sweat will not
evaporate into the air.


As a result, we feel much
hotter than the actual
temperature.
If the relative humidity
is low, we can feel
much cooler than the
actual temperature.

because our sweat
evaporates easily, cooling
the body.
The length of a strand of
human hair changes with
different relative
humidities.
As the relative humidity
increases, hair becomes
longer, and as the humidity
drops it becomes shorter.
On very humid days, your
hair actually becomes
longer and this extra
length causes the
frizziness that gives us
bad hair days.


Sling Psychrometer
It consists of two
identical mercury
thermometers:

Evaporating water
from the wick
absorbs heat
from the
thermometer bulb,
causing the
thermometer reading
to drop.
Find the difference between the DRY bulb and the
WET bulb on the two thermometers
Use the Relative Humidity Table
Where the DRY
bulb temperature
and the
DIFFERENCE
between the two
thermometers
intersects…is
your relative
humidity.
Example – If the DRY bulb temperature reading is
22°C and the DIFFERENCE between the two
thermometers is 6°…the relative humidity is 53%