This document provides instructions for reading a weather map and understanding key elements such as air pressure, wind direction and speed, temperature, and dew point. It explains that air pressure between 94.00 kPa and 106.00 kPa is generally acceptable, how to convert between kPa and millibars, and that changes in air pressure indicate incoming weather. It also outlines how to determine wind direction from arrows on the map and measure speed in knots using barbs. Temperature and dew point are both measured in degrees Celsius.

1. Reading a Weather Map
Predicting the Weather

2. Air Pressure
• Generally acceptable
pressure range is 94.00
kPa to 106.00 kPa
• Add a 9 or 10 in front
of the number and
move the decimal two
places to the left
– ie. 9013 = 90.13 or
10013 = 100.13
• Which air pressure is
acceptable?

3. Air Pressure
• Even if you forget how
to do this, you know
that
– “High means Dry” or
– Low pressure is
associated with really
stormy weather
• The circle tells you the
fraction of cloud cover
• You be the judge

4. Air Pressure
• Converting kPa to millibars
– Multiply by 10
– 100.13 kPa = 1001.3 mb

5. Air Pressure Change
• If 013 translates to
100.13 kPa with 2
decimal places…
– +08 becomes “an
increase of 0.08 kPa”
(notice, 2 decimal places)

6. Wind Direction and Speed
• Thearrow points
towards the circle in the
same direction as the
wind travels.
– ie. Southwesterly
• Wind speed shown by
total barbs
– Each barb = 10 knots
– ½ barb = 5 knots
– ie. 15 knots

7. Temperature
• Measured in degrees
Celsius
– ie. 25°C

8. Dew Point
• The temperature at
which condensation will
occur.
– In other words, when
clouds will form
• Measured in degrees
Celsius
– ie. 19°C