Beaufort Scale
The Beaufort scale is a system of recording wind velocity (speed) devised in 1806
by Francis Beaufort (1774–1857).

Beaufort Number	Description	Features	KPH	MPH
0	Calm	Smoke rises vertically. Water smooth	0 - 2	0 - 1
1	Light Air	Smoke shows wind direction,.Water ruffled	2 - 5	1 - 3
2	Light Breeze	Leaves rustle. Wind felt on face	6 - 11	4 - 7
3	Gentle Beeze	Loose paper blows around	12 - 19	8 - 12
4	Moderate Breeze	Branches sway	20 - 29	13 - 18
5	Fresh Breeze	Small trees sway. Leaves blown off	30 - 39	19 - 24
6	Strong Breeze	Whistling in telephone wires. Sea spray from waves	40 - 50	25 - 31
7	Near Gale	Large trees sway	51 - 61	32 - 38
8	Gale	Twigs break from trees	62 - 74	39 - 46
9	Strong Gale	Branches break from trees	75 - 87	47 - 54
10	Storm	Trees uprooted. Weak buildings collapse	88 - 101	55 - 63
11	Violent Storm	Widespread damage	102 - 117	64 - 73
12	Hurricane	Widespread structural damage	above 118	above 74

Terms

BAROMETRIC PRESSURE	The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the "column" of air lying directly above the point in question. The measurement can be expressed in several ways. One is in millibars. Another is in inches or millimeters of mercury (Hg). Also known as atmospheric pressure.
COOLING DEGREE DAY	A cooling degree day is given for each degree that the daily mean temperature departs above the baseline of 75 degrees a given temperature It is used to estimate the energy requirements, and is an indication of fuel consumption for air conditioning or refrigeration. Refer to degree day or heating degree day.
HEATING DEGREE DAY	One heating degree day is given for each degree that the daily mean temperature is below 65 degrees a given temperature. It is used as an indication of fuel consumption. Refer to degree day or cooling degree day.
DEW POINT	The temperature to which a sample of air must be cooled, while the mixing ratio and barometric pressure remain constant, in order to attain saturation by water vapor. When this temperature is below O°C, it is sometimes called the frost point.
HEAT INDEX	The combination of air temperature and humidity that gives a description of how the temperature feels. This is not the actual air temperature.
HUMIDITY	The amount of water vapor in the air. It is often confused with relative humidity or dew point. Types of humidity include absolute humidity, relative humidity, and specific humidity.
WIND CHILL INDEX	The calculation of temperature that takes into consideration the effects of wind and temperature on the human body. Describes the average loss of body heat and how the temperature feels. This is not the actual air temperature.