A canopy porometer for photosynthesis studies in field crops

A portable, modular porometer for whole-plant or canopy photosynthetic and respiratory gas exchange estimation is described. The system features within-chamber light and temperature measurement and in its present configuration permits analysis of carbon dioxide and water vapour exchange by an extension of the syringe-based "CO2 depletion" technique. Operating characteristics of the system and potential modifications are discussed, along with limitations and applications.

The Production of Clouds Containing Supercooled Water Droplets or Ice Crystals Under Laboratory Conditions

The basic laboratory experiment in which a supercooled cloud may be seeded and converted to ice crystals is described in considerable detail. Such information is given as type and preparation of the cold chamber, light sources which are effective for different purposes, methods to follow in forming supercooled clouds, and procedures to follow in seeding them. The transition temperature at which ice crystals form spontaneously is given as − 39°C ± 0.1°C as the result of a recent study. A simple replica technique for preserving the exact structure of the crystals in plastic is described.