ИСТИНА

In order to emphasis their interest for earth sciences, an outreach program through measurements of frost depth is conducting in Japan. This program is made at elementary, junior high and high schools since 2011 winter in Hokkaido, northern part of Japan where seasonal ground freezing occurs. Frost depth was measured directly once a week at each school by students during ground freezing under no snow-­removal condition. In 2011 season, we started this program at three schools, and the number of participated school is extended to 19 schools in 2013 season, 15 elementary schools, three junior high schools and one high school. We visited schools summer time and just before frost season to talk about the method of measurement. After the end of measured period, we also visited schools to explain measured results by each school and the other schools in Japan and Alaska. The measured values of frost depth in Hokkaido were ranged between 0cm and more than 50cm. We found that the frost depth depends on air temperature and snow depth. We discussed with student why the frost depth ranged widely and explained the effect of snow by using the example of igloo. In order to validate the effect of snow and to compare frost depths, we tried to measure frost depths under snow-­removal and no snow-­removal conditions at one elementary school. At the end of December, depths had no significant difference between these conditions, 11cm and 10cm, and the difference went to 14cm, 27cm and 13cm after one month, with about 30cm of snow depth. After these measurements and lectures, students noticed snow has a role as insulator and affects the frost depth. The network of this program will be expected to expand, finally more than a hundred schools.