Answer to Question 1
ANSWER: The typical cloud-to-ground lightning flash is called negative cloud-to-ground-lightning, because the stroke carries negative charges from the cloud to the ground. About 90 percent of all cloud-to-ground lightning is negative. However, when the base of the cloud is positively charged and the ground negatively charged, a positive cloud-to-ground lightning flash may result. Positive lightning, most common with severe thunderstorms, has the potential to cause more damage because it generates a much higher current level and its flash lasts for a longer duration than negative lightning.
Answer to Question 2
ANSWER: In the United States thunderstorms occur most frequently in the southeastern United States along the Gulf Coast, with a maximum in Florida. The region with the fewest thunderstorms is the Pacific coastal and interior valleys. The reason for this distribution is that the combination of warmth and moisture make equatorial landmasses especially conducive to thunderstorm formation. Here, thunderstorms occur on about one out of every three days. Thunderstorms are also prevalent over water along the intertropical convergence zone, where the low-level convergence of air helps to initiate uplift. Thunderstorms are much less prevalent in dry climates, such as the polar regions and the desert areas dominated by subtropical highs.
(A) Scratch test; patient is exposed to allergens through a light scratch on the skin; (B) Positive
Fossils are formed after an animal dies, decomposes, and is covered in sediment. Minerals in ground
Nonverbal communications convey strong, powerful messages that may be negative or positive.
Cloud Types
Positive and Negative Reinforcement
In the drawing of acetaldehyde, CH3CHO, the largest partial negative charge (-) occurs on