When you say someone is full of hot air you mean they talk a lot but are not sincere.
My boss keeps promising to give me a pay rise but the extra money never comes. He is full of hot air!
Some politicians are full of hot air. They never consider what's best for the nation. Their main concern is what's best for themselves.
To clear the air means to get rid of tension and hard feelings.
Mary and John are having a chat in the kitchen. He was upset after Mary broke up their engagement and she needed to clear the air.
According to the Guinness World Records website, the first Pacific crossing by hot air balloon was achieved by Richard Branson and Per Lindstrand in 1991. The 'Virgin Otsuka Pacific Flyer' flew from the southern tip of Japan to Lac la Matre in Canada. The journey was completed in 46 hours and 15 minutes.