Naohiro Yoshimoto

In order to understand that water vapor, which causes heavy rainfall in Japan during the rainy season and summer, is transported to the vicinity of Japan by the general circulation of the atmosphere on a global scale, we developed and implemented an inquiry teaching material using WEB weather maps. In this practice, three types of WEB weather maps were utilized, and the core of the lesson was for individual students to explore the origin of water vapor in a composite manner based on the cloud, rain, and wind information that could be read from the maps. The results of this practice with third-year lower secondary school students demonstrated that, after the lesson, 71% of the students were able to find and express the possibility that water vapor was transported from at least as far away as the Pacific and Indian Oceans, based on their comprehensive consideration of several different sources of information about the origin of water vapor. Moreover, 77% of the students were able to consider multiple pieces of meteorological information in a composite manner, and this led them to consider the connection between meteorological conditions around Japan and the global atmospheric general circulation. In addition, 37% of the students showed an enhanced interest in weather through the use of the WEB weather maps, and 20% of the students felt that they would like to use the maps in the future. The usefulness of the teaching material using the Web weather maps developed for this study is therefore considered to be effectively demonstrated.

type:Article 中学校理科第2学年「気象とその変化」の「日本の天気の特徴」について,令和2年(2020年)検定済の教科書の分析を行った。冬季における日本の天気の特徴として,すべての教科書において日本海側で雪,太平洋側で晴れとなることが記載されていた。しかし,その特徴を天気図から捉えることができた教科書は一部に限られた。シベリア気団の性質について,すべての教科書で冷たく乾燥していることが記載されていた。しかし,寒冷や乾燥の程度については主文や気団の模式図からは捉えることはできなかった。観測データ等の資料を用いて,冬季における日本の天気の特徴をシベリア気団と関連付けて理解する探究的な学習の方法を提案した。 This study analyzed lower secondary science textbooks for Grade 2, approved in 2020, regarding the “characteristics of Japan's weather" in the “weather and its changes." As characteristics of Japan's weather in winter, all textbooks described that it snows on the side of the Sea of Japan and clears on the side of the Pacific Ocean. However, the textbook, which could catch the features from the weather map, was partly limited. Regarding the characteristics of Siberian air mass, all textbooks described it as being cold and dry. However, the degree to which it was cold and dry could not be conveyed from the main text, or from the schematic diagram of air masses. This study proposes an exploratory learning method to understand the characteristics of Japan's weather in winter by relating them to the Siberian air mass.

<p>Three experiments were conducted using ice balls to model the effects of the compaction, pressure solution, and cementation of sand grains during lithification. In experiment A, two ice balls were stacked together in a plastic pipe, which was then placed in a freezer at temperatures ranging from −14.5°C to −19.6°C. In Experiment B, the same conditions were used, but stainless-steel nuts and bolts weighing 890 g were placed over the stacked ice balls to simulate compaction. After one month, the ice balls in both experiments were bonded together. Thin section observations of the bonded ice balls from Experiment A showed that the contacts between ice balls resembled the long contacts of sand grains formed during pressure solution. In Experiment C, two ice balls were placed together in a plastic pipe filled with warm air (33.0°C and 46% relative humidity), which was then sealed with a plastic covering and placed in a freezer at temperatures ranging from −17.8°C to −20.0°C. Two months later, these ice balls were cemented together by fine interstitial ice crystals, indicating the formation of an ice cement between ice balls. These results suggest that ice ball experiments can be used to model the processes of clastic lithification by pressure solution and interstitial cementation, thus providing a better understanding of the consolidation of sands.</p>

Two longitudinal-mode snowbands (bands I and II) were observed over the Ishikari Bay, Hokkaido, Japan during a wintertime cold-air outbreak. The three-dimensional kinematic structure of a snowband (band II) was examined in detail using dual-Doppler radar data. Band II noticeably developed over the Ishikari Bay. A high-reflectivity (approximately 35 dBZ at the maximum) zone was formed along the band axis and characterized the radar-echo structure of band II. The high-reflectivity zone of band II had the airflow structure dominated by circulations in vertical cross sections perpendicular to the band axis. The interactions between the two snowbands were discussed. Interestingly, it was found that radar-echo bridges existed at the low levels between the two snowbands. The radar-echo bridges were formed in association with low-level outflows from the meso-gamma-scale convective cloud systems composing band I. The low-level outflows moved toward band II with time and penetrated into band II. This caused strong low-level convergence and the enhancement of updrafts in band II. Consequently, stronger radar-echoes were formed in band II and band II rapidly developed. Ice/snow particles were transported from band I into band II by the low-level outflows. It was considered that the rapid growth of these particles in the enhanced updrafts in band II would have contributed to the rapid development of band II.

The orographic modification of a precipitating convective cloud, which formed in association with typhoon 9304 and travelled over the sea, was studied by mainly analyzing the dual-Doppler radar system observational data. From July 24 1900 LST, to July 25 0000 LST, many convective clouds landed at the southeastern coast of the Kii Peninsula. Although they reached the coast in various stages of development, most of them showed similar features. Their radar-echoes were intensified 10 to 20 km off the coast before landing, and the radar-echoes were intensified again or broadened over land after their radar-echo intensities were reduced near the coast. Before the first intensification of convective radar-echoes over the sea, the echoes were intensified in their upper rear-parts 30 to 40 km off the coast, and intensified in their front-parts near the coast. By averaging horizontal winds derived from the dual-Doppler radar system observational data for about two hours, it was shown that the ambient wind speed decreased near the coast, and the horizontal convergence zone larger than 10(-4) s(-1) existed along the coast line about 10 km off the coast. On the basis of these observational results the travelling convective clouds orographic modification, and the efficient formation of precipitation in them were discussed, taking into account the results of numerical experiment about the Kii Peninsula orographic effect on ambient winds. It can be inferred that the large rainfall amount recorded in association with the typhoon around the Kii Peninsula coast was caused as a result of the integration of travelling convective clouds orographic modification.

Observations of snowstorms were carried out around Ishikari Bay, Hokkaido, Japan, from December 1991 to February 1992. On 15 January 1992, a longitudinal-mode snowband was observed by a dual-Doppler radar system. The snowband was composed of meso-gamma-scale (similar to 20 km) convective cloud systems. The three-dimensional kinematic structures and organization processes of the meso-gamma-scale systems were studied in detail. Strong band-parallel winds appeared in the upper-north rear of the meso-gamma-scale systems. Since their speed was faster than that of the cellular radar echoes, the winds formed rear-to-front currents. Increasing in volume and speed, the rear-to-front currents developed into meso-gamma scale and penetrated toward the lower front and lower south of the systems. Consequently, the rear-to-front currents caused strong meso-gamma-scale convergence and the enhancement of updrafts at their leading edges. The transport of the band-parallel momentum greatly contributed to the successive development of new convective cells within the systems and the organization of the meso-gamma-scale systems in the snowband. Ice/snow particles were transported by the updrafts toward the rear and north of the systems in the overlying stable layer. They then evaporated outside the clouds. The downdraft caused by evaporative cooling played an important role in the transport of band-parallel momentum from the upper to the lower levels and from the outside to the inside of the snowband.

During outbreaks of the winter monsoon, snow clouds in the winter season over Ishikari Bay, Hokkaido, take the form of band shape. In order to analyze the process of radar echo organization, time change of echo areas and shape features were analyzed statistically using PPI (Plan Position Indicator) radar echo images. On an average, echo area incresed and echo shape elongated with time.