The first lines of “Scatterbrain,” the 13th song on Hail to the Thief read:
I’m walking out in a force ten gale
birds thrown around, bullets for hail
the roof is pulling off by its fingernails
The most common definition of gale is simply “wind.” In the OED, the third definition reads:
“1. a. A wind of considerable strength; in nautical language, the word chiefly â€˜implies what on shore is called a stormâ€™ (Adm Smyth), esp. in the phrases strong, hard gale (a stiff gale is less violent, a fresh gale still less so); in popular literary use, â€˜a wind not tempestuous, but stronger than a breezeâ€™ (J.). Also gale of wind. In restricted use, applied to a wind having a velocity within certain limits (see quots.).”
Today, in stricter meteorological terms, a gale’s force is measured on the Beaufort Scale. One of the most detailed accounts of the scale’s history is available here. As you can see comparing the above Beaufort Scale to the one maintained by the US National Weather Service Storm Prediction Center, a force ten wind is often termed a “storm” or a “whole gale.” Generally, however, these and various other versions of the scale agree that a force ten gale is a wind in which the sea turns white, trees can be uprooted and building damage occurs.
Historically, the definition of gale has shifted slightly as these entries in the OED indicate:
“1923 N. SHAW Forecasting Weather (ed. 2) 456 As a result of the investigation of 1905 we now classify winds with velocity above 75 miles per hour as hurricane winds, those with velocity between 64 and 75 miles per hour as storm winds, and those between 39 and 63 as gales. 1963 Meteorol. Gloss. (Met. Office) 109 Gale, a wind of a speed between 34 and 40 knots (force 8 on the Beaufort scale of wind force, where it was originally described as â€˜fresh galeâ€™), at a free exposure 10 metres (33 feet) above ground. Ibid., Statistics of gales refer to the attainment of mean speeds of 34 knots or over.”
In the OED, the second definition of the word, now obsolete, has two entries, the first is subdivided: 1a. Singing, a song; merriment, mirth; 1b. said of the voice of an animal; and 2. Speech, talk.