The surface expression of the Gulf Stream front was determined between Miami, Florida and 70 deg W longitude from Stommel-Parson air-borne radiation thermometer data and photographic and visual observations. Visual and thermometric evidence of the frontal outcrop on the sea surface was discontinuous. The radiation thermometer alone was considered the most reliable index of the front during winter months. The problem is discussed of relating the surface evidence obtained from the air to the meander structure observed from ships. The aerially observed discontinuities may be superficial phenomena, while the frontal structure obtained from the relatively wide-spaced bathythermograph observations and ship crossing may be excessively smoothed.