Coherence between EEG signals at specific frequencies is often used as a measure of functional connectivity between brain areas. This study investigated the components of coherence in EEG at the alpha frequency across scalp locations, focusing on the relative contributions of amplitude-correlation and phase-locking. Using simulations, we demonstrate how coherence is influenced by the combination of three factors: phase-locking, amplitude-correlation, and amplitude-variability. At empirically realistic levels of amplitude-variability, phase-locking had a stronger effect on coherence than amplitude-correlation. Empirical EEG data collected from 165 participants during an eyes-closed condition revealed that across participant-variations in phase-locking strength and amplitude-correlation were only weakly associated for frontal - occipital electrode pairs, which are least affected by volume conduction and thus provide the most interpretable measures of functional connectivity. This dissociation suggests that phase-locking and amplitude-correlation should be analyzed separately as distinct indicators of functional connectivity rather than being combined in the compound measure of coherence. Additionally, exploratory phase-analyses showed that most participants exhibited systematic plane traveling waves in either the anterior-posterior (backward) direction or posterior-anterior (forward) direction. Backward waves were approximately twice as common as forward waves. Interestingly, the scalp distribution of alpha amplitude was independent of the direction of wave travel, further highlighting the dissociation between alpha phase and amplitude dynamics. These findings provide new insights into the mechanisms underlying EEG coherence and traveling waves, with implications for understanding large-scale cortical dynamics during resting-state conditions.