1. Surface Weather Observations
(Worldwide, every 3 Hours GMT starting at 00:00)
Current and past state of the weather e.g. Rain, Fog, etc.
Air temperature
Dry bulb temperature
(Wet bulb temperature)
Maximum, minimum temperatures

2. Surface Observations (continued)
Relative humidity Amount and type of clouds Wind speed and direction Pressure, pressure tendency Precipitation

3. Psychrometers – Hygrometers
Measure humidity and/or dew point
Sling psychrometers use wet and dry bulb thermometers.

4. Other instruments (many)

5. Earth

6. Clouds Aid in weather forecasting Trace atmospheric motions
(e.g. satellite imagery)
Produce precipitation
Reflect sunlight away from Earth
Absorb/emit heat radiation
Absorb or rainout air pollution

7. Luke Howard ( )
In 1803 introduced terminology for clouds based on their appearance, i.e. altitude, size, shape, and texture.

8. High-Level
(> 20 kft)
Ice crystals
Cirrus (Ci)
Cirrocumulus (Cc)
Cirrostratus (Cs)

9. Mid-Level
(6.5 to 20 kft)
Mixed phase (i.e. water drops and ice crystals)
Altocumulus (Ac)
Altostratus (As)

10. Low-Level
(up to 6500 ft)
Water drops
Cumulus (Cu)
Stratocumulus (Sc)
Stratus (St)

11. “Nimbo-” or
“-nimbus”
means cloud is producing precipitation.
e.g. Cumulonimbus, Cb (thunderstorm)
Nimbostratus, Ns (rain or snow)

12. Tower of the winds in Athens, Greece (drawn in 1762)

14. (18th Century reconstruction, original c 48 B.C.)

15. Wind Vane or Weather Vane
Measures direction wind is blowing FROM

16. Artistic wind vanes

17. Wind vane on George Washington’s home at Mount Vernon

18. “Dove of Peace” by Joseph Rakestraw (1787)

19. Thomas Jefferson’s wind vane at Monticello.

20. Robinson cup anemometer (1795)
Munro (1870)

21. Windmill anemometer measures wind speed and direction

22. Sonic anemometer
Laser anemometer

23. Magdeburg hemispheres used to illustrate force produced by air pressure.

24. Water barometers
Berti (1639) in Rome Guericke (c1654) in Magdeburg

25. In 1644, Torricelli wrote in a letter: "We live submerged at the bottom of an ocean of air."

26. Height of mercury is independent of shape of tube

28. Fortin
(Mercury)
Barometer

29. Weather glass or Thunder glass
Used to measure CHANGES
in atmospheric pressure (or temperature)
"decreasing pressure predicts
stormy weather"

30. Aneroid barometer – sealed metal case expands or contracts in response to variations in atmospheric pressure.
High
Low
Levers magnify these changes, causing a pointer to move on a dial, or numbers to change on a digital read-out device.

32. Aneroid microbarograph

33. Rain gauges measure depth of precipitation that occurred. over a
Rain gauges measure depth of precipitation that occurred over a (known) area, or volume of rain per unit area
Basic
Gauge
Tipping bucket and recorder gives time