The special dry warm wind that blows from the Rocky Mountains down into valleys below is called a Chinook wind.

Here's why:

* Warm: The Chinook wind is warm because it descends from higher altitudes where the air is colder. As it descends, it is compressed and warms adiabatically (due to the increase in pressure).

* Dry: The Chinook wind is dry because the moisture in the air condenses out as the air cools at higher altitudes.

* Special: The Chinook wind is a unique phenomenon that occurs in specific geographic locations. It's responsible for dramatic temperature swings in areas near the Rocky Mountains.

Let me know if you have any other questions about the Chinook wind!