Intermittent sun exposure
In many countries like the UK, many people are not exposed to sunlight for most part of the year. However, people have been moving abroad for 2-3 weeks over the past couple of decades to a sun tan.
Studies have demonstrated that the risk of melanoma has significantly increased in people who go outside for the holidays. People who are exposed to even short-term but intense sunlight, like holidaying in the hot country, are more prone to develop melanoma than people who are regularly exposed to sunlight.
Similarly people with high socioeconomic status are also at a higher risk – because they usually confined themselves to closed spaces and don’t get enough sun exposure. Partially, this is because they take more foreign holidays and thus are more exposed to intermittent sunlight. But there may be other factors involved.