The behavior of a sound wave is affected by the density of the medium, the temperature of the medium and the pressure of the medium if it is a gas. Motion of the medium independent of the sound wave may also affect the way sound propagates.
Yes, you may check-in for your Delta Air Lines (DL) flight with your mobile device starting 24 hours and ending 60 minutes before the scheduled departure time (depending on your departure city and destination) to receive a mobile boarding pass on your mobile device.
Delta currently does not charge passengers for checking a first bag on domestic flights. It has said it is studying a decision by several other major carriers to impose that fee. Delta customers checking bags on international flights can check a first and second bag at no charge. Fees are for each extra bag, each way.The fee for checking a third bag on a domestic flight will increase from $80 to $125, while the fee for checking a bag that is between 51 and 70 pounds on a domestic flight will rise from $80 to $90.elta currently does not charge passengers for checking a first bag on domestic flights. It has said it is studying a decision by several other major carriers to impose that fee. Delta customers checking bags on international flights can check a first and second bag at no charge. Fees are for each extra bag, each way.