Chapter 8 Science

Precipitation *In order for precipitation to occur, cloud droplets or ice crystals must be heavy enough to fall through. One way is when water droplets combine with other droplets

- Form of water that falls from clouds and reaches Earth's surface

Anticyclone

- High pressure center of dry air - H for high pressure zone - Winds spiral out and move toward a low pressure area Clockwise in N Hemisphere because of Coriolis Effect - The Descending air in a anticyclone causes dry clear weather

Psycrometer

- Instrument used to measure relative humidity which consists of a wet and dry bulb thermometer - The wet bulb is covered with a moistured cloth and when spun is cooled by evaporation - When the rel. humidity is high, the water on the wet bulb evaporates slowly and does not change as much. When the rel. humidity is low, the water evaporates rapidly and the temp. drops * Rel. humidity is found when comparing the two thermometers.

Humidity * Warm air can hold more water vapor than cool air*

- Measure of the amount of water vapor in the air

Condensation The two conditions in order for condensation to occur is the _____ of _____ and the prescence of _____ in the air

- Process in which molecules in water vapor condense to form liquid water cooling, air, particles - When cold air cools(*cold air holds less water vapor than warm air) the amount of water vapor decreases and condenses to form clouds - - Particles like from salt crystals, dust from soil and smoke need to be present so water has something to condense on

Cyclone

- Swirling center of low pressure " wheel' - L stands for a low pressure zone - Counter Clockwise: Northern Hemisphere Clockwise: Southern Hemisphere - Spiral In

Dew Point

- Temp. at which condensation occurs - If below freezing, water vapor can directly change into crystals

Water Cycle What powers the water cycle? Go over the water cycle...

- The continuous movement of water between the atmosphere and the Earth's surface - The sun's radiation

Relative Humidity

- The percentage of water vapor compared to the maximum amount of water vapor that the air can hold at a specific temp. Ex: at 10C , 1 cubic meter of air can hold 8 grams of water vapor - If true, the relative humidity would be 100% but if it can only hold 4 grams, the relative humidity would be 50%

Evaporation

- The process by which water molecules in liquid water absorb energy

Hurricane

A *tropical cyclone* that has winds of 119 km per hour or higher - 600 km across - Form in Atlantic, Pacific( typhoons), and Indian Ocean - Begins over warm ocean water as low- pressure area which grows in size and stength to form a hurricane - Draws energy from warm ocean waters but loses energy as it passes land - Brings high winds and severe flooding

Storm Surge

A dome of water that sweeps across the coast where a hurricane lands

How do clouds form?

Clouds form when warm, moist air rises and cools. Water vapor condenses on tiny particles to form liquid water or ice crystals.

What are the different types of fronts?

Cold Fronts- form when rapidly moving cool air collides with slowly moving warm air and the cool air slides under the warm air ( Heavy rain or snow and thunderstorms can occur) Warm Fronts- forms when a fast moving warm air mass overtakes a slowly moving cold air mass( If dry scattered clouds form if humid, light rain or snow falls) Stationary Front- form when cold and warm air masses can not move eachother (rain, snow, clouds, fog) Occluded Fronts- warm air mass is caught between two cooler air masses and pushes the warm air up

Weather associated with an anticyclone is generally?

Dry and Clear

How do low pressure areas form?

Fronts can become twisted and pulled out of shape from jet streams and prevailing westerlies which begin to swirl and form a low pressure center

What are stratocumulus clouds?

Gray or whitish patch, sheet, or layered clouds

What is true about the eye of the hurricane?

It is calm

Tornado Alley includes which states?

Kansas, Texas

IsoBARS

Lines joining places with the same AIR PRESSURE

IsotTHERMS

Lines joining places with the same TEMP

What are the three main types of clouds and their characteristics?

Main Types: Cirrus- wispy, feathery clouds that occur at high altitudes and are made of ice crystals " Curl of hair" Cumulus- fluffy (likerounds of cotton) which grow in size and height Stratus- flat layers, spread out where drizzle and mist fall from - Alto: high - Nimbus: tall

Air masses are commonly moved by prevailing westerlies and jet streams. What are these wind belts? *Cold temps. have high pressure and high temps have low pressure*

Prevailing Westerlies- wind belts that push air from west to east Jet Streams- Band of high winds within Prevailing westerlies

What are the different types of precipitation?

Rain- drops of water that are 0.5 millimeter in diameter Hail- Round pellets larger than 5 milliliter in diameter which fall as they form layers of ice when moving through colder areas in cumulonimbus clouds Snow- water vapor in a cloud that is directly converted to snowflakes; ice crystals under 32F Sleet- raindrops that freeze through the air and the small version of hail Freezing rain- raindrops that freeze once they touch the ground

Tornado

Rapidly whirring funnel- shaped cloud that reaches to earth's surface - If over a lake or ocean it is a waterspout - Speeds up to 500 kph - Often form in spring and summer mostly in tornado alley - During a tornado the best place to be is in a storm sheter or the basement of a well- built building - Fujita Scale

Meteorologists

Scientists who study the causes of weather and predict - they collect data to predict weather Ex: Use many instruments such as maps and charts to analyze and predict

Thunderstorm

Small storm accompanied by heavy precipitation - Form in cumulonimbus clouds only - When warm humid air cools, dense thunderheads form - When updrafts and downdrafts of wind are pesent in thunderheads, thunderstorms occur

What is 74 mph?

Speed needed for a hurricane to become a hurricane

Lightning

Sudden spark or electric discharge - When lightning bolt heats the air to a really high temp, the air expands suddenly and explosively. The sound is thunder - Lightning and thunderstorms can cause damages to people and nature Ex: Floods, forest fires - During a thunderstorm, avoid places where lightning may strike and of objects that can conduct electricity(stay in car)

What are the four main air masses and their characteristics?

Temp Characteristics: Tropical- warm air masses that form in the tropics and have low air pressure Polar- cold air masses that form north of 50N and south of 50S and have high pressure Moisture Content: Maritime- air masses that form over oceans and are very humid Continental- air masses that form over land and are dry Maritime Tropical- MOIST AND WARM Warm humid air masses that form over *tropical oceans which usually form over the Gulf of Mexico and the Atlantic ocean* Maritime Polar- MOIST AND COLD Cool humid air masses that form over the *North Pacific and North Atlantic* and brings fog, rain, and cool temps to the West Coast Continental Tropical- DRY AND WARM hot dry air masses that form the *southwest and northern mexico in summer* Continental Polar- DRY AND COLD Form over *Northern Canada and Alaska* and bring bittery,cold air with low humidity

Front

The boundary where air masses meet * Warm air (less dense) floats over cool air (denser mass)

Storm

Violent disturbance in the atmosphere - Scientists look for fulgurites as evidence - Involve with sudden changes in air pressure which can cause rapid air movements

Hurricanes typically form over?

Warm ocean water

Air mass

body of air that has similar temp, humidity, and air pressure at any given height

Thin, white patch, sheet, or layered clouds

cirrocumulus clouds

What are nimbostratus clouds?

rain clouds

Clouds are millions of tiny _____ _____ or ____ _____. Clouds form when ____ ___ in the air condenses to form __ ____ or _____ ___.

water droplets, ice crystals, water vapor, liquid water, ice crystals