The Student Nitric Oxide Explorer (SNOE) satellite has been observing Polar Mesospheric Clouds (PMCs) since 1998 and has successfully measured seven PMC seasons. In the summer seasons, the Ultraviolet Spectrometer (UVS) limb measurements include detections of PMCs between 80 -- 90 km. SNOE observations of PMCs have a significant advantage over other PMC measurements in that it can observe them globally each day. Because SNOE orbits the earth 15 times a day, daily global images of PMC brightness may be produced. Variations in the PMC brightness with a 5-day period are observed from the measurements. The 5-day wave is observed in both the northern and southern hemisphere polar summers at high latitudes. This is the first direct global scale wave analysis performed on PMC measurements and indicates the effects of dynamics on PMC formation.