Hot Air Meaning

Example :   The balloon was equipped with a burner to create hot air for lift.1913, William MacLeod Raine, The Vision Splendid, ch. 8:  "You'll never get anywhere so long as youse trail with that reform bunch. It's all hot air and tomfool theory."1921, Alice Hegan Rice, Quin, ch. 28:  "You give me a lot of hot air about your conscience. Why don't you get a soap-box and preach on the street-corners?"2001 June 24, Johanna McGeary, "How Bad Is China?," Time (retrieved 22 Sept 2013):  Some of the steam in Washington rises from real issues, but a lot is the hot air of partisan politics.