Teaching Meteorology on the Web: A Student\u27s Perspective

Many university courses have been taught in recent years with the web as a supplemental or a primary teaching environment and learning resource (e.g. the Western Governor\u27s concept of Virtual University; Resmer et al 1995). Many variants exist, and questions remain about the effect of web-based teaching on teaching effectiveness and on the learning process (e.g. FABIT 1995). How, for instance, does the web assist in preparing lecture material, in visualizing concepts, and in evaluating student performance? And how is the student\u27s learning affected, in particular his/her in-depth understanding of concepts, reasoning skills, and problem-solving skills? Ultimately we should ask whether we prepare the students better for the career they are aspiring to

Characterization of Mesoscale Convective Systems by Means of Composite Radar Reflectivity Data

A mesoscale convective system (MCS) is broadly defined as a cloud and precipitation system of mesoscale dimensions (often too large for most aircraft to circumnavigate) with deep-convective activity concentrated in at least part of the MCS, or present during part of its evolution. A large areal fraction of MCSs is stratiform in nature, yet estimates from MCSs over the Great Plains, the Southeast, and tropical waters indicate that at least half of the precipitation is of convective origin. The presence of localized convection is important, because within convective towers cloud particles and hydrometeors are carried upward towards the cloud top. Ice crystals then move over more stratiform regions, either laterally, or through in situ settling over decaying and spreading convection. These ice crystals then grow to precipitation-size particles in mid- to upper tropospheric mesoscale updrafts. The convective portion of a MCS is often a more or less continuous line of thunderstorms, and may be either short-lived or long-lived. Geerts (1997) presents a preliminary climatology of MCSs in the southeastern USA, using just one year of composite digital radar reflectivity data. In this study MCSs are identified and characterized by means of visual inspection of animated images. A total of 398 MCSs were identified. In the warm season MCSs were found to be about twice as frequent as in the cold season. The average lifetime and maximum length of MCSs are 9 hours, and 350 km, respectively, but some MCSs are much larger and more persistent. In the summer months small and short-lived MCSs are relatively more common, whereas in winter larger and longer-lived systems occur more frequently. MCSs occur more commonly in the afternoon, in phase with thunderstorm activity, but the amplitude of the diurnal cycle is small compared to that of observed thunderstorms. It is estimated that in the Southeast more than half of all precipitation and severe weather results from MCSs

A Tight Upper Bound on the Number of Candidate Patterns

In the context of mining for frequent patterns using the standard levelwise algorithm, the following question arises: given the current level and the current set of frequent patterns, what is the maximal number of candidate patterns that can be generated on the next level? We answer this question by providing a tight upper bound, derived from a combinatorial result from the sixties by Kruskal and Katona. Our result is useful to reduce the number of database scans

Freight Transportation Planning on the European Multimodal Network: the case of the Walloon Region

This paper presents a methodology that can be used for long-term planning of freight transportation on multimodal networks. It is illustrated by research carried out for the Belgian Walloon Ministry of Transport between 1997 and 1999. Its aim was to provide a tool for measuring the impacts of different kinds of policies and/or new infrastructures on freight transport flows in and through Wallonia. The work started with the setting up of a calibrated multimodal and multi-products reference scenario for the year 1995. This reference scenario was then used as a basis to create a projection for the year 2010: in order to make this projection as realistic as possible, all the decided new infrastructures in Belgium and in the border countries that will be effective in 2010 were introduced in the model. Moreover, expected changes in the O-D matrixes were also introduced at a very detailed level. Then, a set of scenarios was build: one for each transportation mode in which specific changes for that mode were introduced, and one in which the external costs of transport were taken into account. On the basis of the obtained results, a ætransportation planÆ was built, in which the most promising changes in the different networks and policies were chosen. A sensitivity analysis (low and high economic activity) was finally performed

The Impact of Ground-Based Glaciogenic Seeding on a Shallow Stratiform Cloud over the Sierra Madre in Wyoming: A Multi-Sensor Study of the 3 March 2012 Case

A case study is presented of the impact of ground-based glaciogenic seeding on a shallow, lightly precipitating orographic storm with abundant supercooled cloud droplets, but few ice particles. The storm was observed on 3 March 2012 as part of the AgI (silver iodide) Seeding Cloud Impact Investigating (ASCII) experiment in Wyoming. The cloud base temperature was about -9°C, and cloud tops were at about -16°C. The high concentration of small droplets and low ice particle concentration lead to natural snow growth, mainly by vapor diffusion. The question addressed here is whether the injection of ice nucleating particles (AgI) enhanced snow growth and snowfall. The treated (seeded) period is compared with the preceding untreated (noseeded) period, and natural trends (observed in an adjacent control region) are removed. The main target site, located on a mountain pass at an elevation above cloud base, was impacted by AgI seeding, according to a trace chemistry analysis of freshly fallen snow. Data from three radar systems were used: the Wyoming Cloud Radar, two Ka-band profiling Micro-Rain Radars, and a X-band scanning Doppler-on-Wheels (DOW) radar. Composite data from these radar systems and from gauges in the target area indicate an increase in low-level reflectivity and precipitation rate during seeding. This finding generally agrees with other published ASCII case studies. The increase in reflectivity during seeding in the target area appears to be due mainly to an increase in particle size (aggregation), not number concentration, as suggested by DOW differential reflectivity and by disdrometer and Cloud Particle Imager measurements on the ground

Painting With Light: Artistic Experiments into the use of Virtual Reality as an Animation Production Environment

While many researchers have examined the technical characteristics of using VR as a production environment for animation, its artistic potential has only sporadically been investigated. We want to contribute to this line of thought through reflection on a number of expanded animation workshops organized in the context of the Painting With Light project. In this paper we use flow theory in order to discuss the experience of using VR as a 3D prototyping tool. Our findings suggest that this practice can add an improvisatory and co-creative dimension to animation