Sometimes the temperature does not decrease with height in the troposphere, but increases. Such a situation is known as a temperature inversion. Temperature inversions limit or prevent the vertical mixing of air.
Middle range machines can cost on average $400 and are often multi-function with copier and laser printer capabilities. Finally, high-end machines which offer high speeds, high capacity and high resolution come at a higher price-expect to pay $1000 - $2500 for such a fax machine.
1 Regular monthly price is $9.99 for Fax 500, 2  $17.99 for Fax 1000, $59.99 for Fax 2500, $49.99 for Fax Unlimited, if paid on monthly basis. 3  Plan includes specified number of pages; fax pages count assumes the average document takes 1 minute per page to send.