What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands?

By long-standing convention and practical advantage, amateur radio operators use horizontal polarization for weak-signal VHF and UHF modes, which include Continuous Wave (CW) and Single Sideband (SSB). Most directional antennas, like Yagis, are mounted horizontally for these modes to minimize picking up local man-made noise, which is predominantly vertically polarized. Conversely, FM repeater and simplex communications typically use vertical polarization because mobile stations use vertical whip antennas. If you were to use a vertically polarized antenna for CW or SSB while everyone else is using horizontal, you would suffer a massive signal loss. Circular polarization is generally reserved for satellite communications, where the orientation of the spacecraft's antenna constantly changes relative to the ground.