depression definition. A period of drastic decline in the national economy, characterized by decreasing business activity, falling prices, and unemployment. The best known of such periods is the Great Depression, which occurred in the 1930s.
A variometer â also known as a rate of climb and descent indicator (RCDI), rate-of-climb indicator, vertical speed indicator (VSI), or vertical velocity indicator (VVI) â is one of the flight instruments in an aircraft used to inform the pilot of the rate of descent or climb.
Vertical Motion is a change in altititude (height). Horizonal Motion is a change in ground track position (i.e., a change in what spot the object is directly over). Often, an object's motion has both a vertical component and a horizontal component (for example when it does diagonally up or diagonally down).