Chapter 16 Earth Science WEATHER

Words to Know – Section 1 What is weather? humidity relative humidity dew point Fog precipitation

state of the atmosphere at a specific time and place, determined by factors including air pressure, temperature, wind, and precipitation weather

amount of water vapor held in the air humidity

measure of the amount of moisture held in the air compared with the amount it can hold at a given temperature; 0 percent to 100 percent relative humidity

temperature at which air is saturated and condensation forms dew point

a stratus cloud that forms when air is cooled to its dew point near the ground fog

water falling from clouds – including rain, snow, sleet ,and hail – whose form is determined by air temperature precipitation

Words to Know – Section 2 Weather Patterns air mass front tornado hurricane Blizzard spring

large body of air that has the same characteristics of temperature and moisture content as the part of Earth’s surface over which it formed air mass

boundary between two air masses with different temperatures , density, or moisture; can be cold, warm, occluded, and stationary front

violent, whirling windstorm that crosses land in a narrow path and can result from wind shears inside a thunderhead tornado

large, severe storm that forms over tropical oceans, has winds of at least 120 km/h, and loses power when it reaches land hurricane

winter storm that lasts at least three hours with temperatures of -12 degrees C or below, poor visibility, and winds of at least 51 km/h blizzard

forms when the water table meets Earth’s surface; often found on hillsides and used as a fresh-water source spring

Words to Know – Section 3 Weather Forecasts meteorologist station model Isotherm isobar

studies weather and uses information from Dopplar radar, weather satellites, computers and other instruments to make weather maps and provide forecasts meteorologist

indicates weather conditions at a specific location, using a combination of symbols on a map station model

line drawn on a weather map that connects points hacing equal temperature isotherm

lines drawn on a weather map that connect points having equal atmospheric pressure; also indicate the location of high – and low-pressure areas and can show wind speeds isobar