The skip distance of a sky wave will be greatest when the:

The distance a sky-wave signal travels in a single "hop" depends heavily on its takeoff angle—the angle between the ground and the emitted radiation. When this angle is very small (closest to the horizon), the radio wave strikes the ionosphere at a very shallow, glancing angle, causing it to return to Earth much further away. Conversely, if the takeoff angle is high (steep), the signal travels a shorter distance along the ground before returning, or it may escape into space entirely if it exceeds the critical angle. Therefore, lower takeoff angles result in the greatest possible skip distance. Signal strength and antenna polarization do not change the geometric path of the wave. While a densely ionized layer helps refract signals, it tends to bend them more sharply, potentially decreasing rather than increasing the skip distance for a given frequency.