What electromagnetic wave polarization does a half-wavelength antenna have when it is perpendicular to the Earth's surface?

When an antenna is mounted perpendicular (straight up and down) relative to the Earth's surface, it produces vertically polarized electromagnetic waves. This is because an antenna's polarization is determined by the electric field, which physically aligns with the radiating element. Horizontal polarization would require the antenna to be parallel to the ground. Circular and elliptical polarizations are generated by specialized antennas, such as helicals or crossed dipoles, rather than a single perpendicular half-wavelength wire.