A device for cooling sheets of glass by jets of air emitted by at least one nozzle in a form of a pipe, including a box supplying the nozzle with air, airflow ejected via an ejection orifice of the nozzle passing successively through a conical part, of which an internal section is reduced in a flow direction, and then through a cylindrical part including the ejection orifice, of which an internal section corresponds to a smallest internal section of the conical part and to an internal section of the ejection orifice. The cylindrical part of the nozzle has a length greater than 6 times the diameter of the ejection orifice. The device achieves a high level of heat exchange when the sheets of glass are cooled, which makes it possible to increase reinforcing effect on the glass and/or to reduce power of fans used to convey air through the nozzles.