Willy-Willy - A term most commonly used in Australia referring to a dust devil. Dust devils are small, rapidly rotating columns of wind that are made visible by dust or dirt that get sucked into them. They are most commonly seen in the afternoon on hot, dry days.

Saturation - An atmospheric condition whereby the level of water vapor is the maximum possible at the existing temperature and pressure. Air has a greater capacity for water vapor as the temperature increases. This is because air molecules become less densely packed when the temperature rises, thereby giving more room for water vapor to occupy. The air reaches saturation any time that the dew point and temperature are the same. This can lead to the formation of fog.

Barometer - An instrument used to monitor variations in air pressure at the surface. The first barometer was invented by the Italian physicist Torricelli in 1643. For the centuries to follow, the barometer was the main tool used in weather forecasting.

Azores High - Also known as the Bermuda high, this is a large, persistent, atmospheric high-pressure center that develops over the subtropical region of the eastern North Atlantic Ocean. The position of this high will migrate between Bermuda and the Azores Islands throughout the course of a year.

Drought - An extended period of abnormally dry weather that creates shortfalls in the amount of surface and/or subsurface water. Droughts have major impacts on agriculture and can have major socioeconomic consequences as well.

Altostratus Clouds - Are gray or blue-gray middle level clouds composed of ice crystals and water droplets. These clouds usually cover the entire sky. In the thinner areas of the cloud, the sun may be dimly visible as a round disk.

Transpiration - The process by which water escapes plants into the air and turns into water vapor. The rate at which plants lose water to the air increases as the temperature increases. Corn plants transpire at a rate higher than most plants. This means that corn needs more moisture to survive compared to most plant life.