Lettuce. Lettuce is a fairly hardy, cool-weather vegetable that thrives when the average daily temperature is between 60 and 70Â°F. It should be planted in early spring or late summer. At high temperatures, growth is stunted, the leaves may be bitter and the seedstalk forms and elongates rapidly.ipburn is a physiological condition that causes lettuce to die back at the edges of the leaves. It results from a change in the moisture relationship between the soil and the plant. Clip off any brown leaf tissue and use the remainder of the leaf.
chromosphere. A layer of gas that lies above the photosphere of a star, such as the Sun. Thesaurus Antonyms Related Words Synonyms Legend: Switch to new thesaurus . Noun: 1. chromosphere - a gaseous layer of the sun's atmosphere (extending from the photosphere to the corona) that is visible during a total eclipse of the sun layer - a relatively thin sheetlike expanse or region lying over or under another
(1) When a star exhausts the hydrogen in its core, it becomes a giant or supergiant. The layer immediately above the core becomes hot enough to initiate the fusion of hydrogen into helium. The star now has THREE main layers: ( 1 1) Helium core (inner layer): Releases energy as it shrinks in radius. ( 2 2) Fusion shell: Releases energy as it fuses hydrogen into helium. ( 3 3) Hydrogen envelope (outer layer): Absorbs energy, and swells greatly in size.