Measurements of atmospheric ions in the size range 0.8-42 nm were conducted at the environmental research station of the University of Crete at Finokalia from April 2008 to April 2009 in the frame of the EUCAARI project. Both positive and negative atmospheric ions were found to have a clear annual cycle, with minimum concentrations in summer. Their concentrations were found to strongly vary on the prevailing meteorology and the presence of pollutants in the atmosphere. There were 53 new particle formation events recorded. It was found that under certain meteorological conditions and atmospheric composition, enhanced ion concentrations can be observed during the night. Overall, 39 night-time events were observed, all of them observed for the negatively charged particles while only 21 were observed for the positively charged particles. Night-time enhanced ion concentrations were more frequent during spring and autumn and no such events were recorded from July to September. It was found that the presence of pollutants in the atmosphere leads to a decrease of atmospheric ions, especially at cluster sizes (1.25-1.66 nm). Additionally, the meteorological conditions affect the abundance of atmospheric ions greatly, a strong anti-correlation was found between air ions concentrations on the one hand and temperature and wind velocity on the other. Enhanced ion concentrations at night were found to be more frequent when air masses had traveled over the island of Crete.