Weather Temporary behavior of atmosphere (what’s going on at any certain time) Small geographic area Can change rapidly

Severe weather Refers to any dangerous meteorological phenomena with the potential to cause damage, serious social disruption, or loss of human life.

Weather --The study of weather is meteorology --Someone who studies weather is called a meteorologist Forecast is a prediction or estimate of future events, especially coming weather

Temperature a measure of how hot or cold something is; specifically a measure of the average kinetic energy of the particles in an object, a type of energy associated with motion. Thermometer is an instrument for measuring and indicating temperature

Thunderstorms Requires a mature cumulonimbus cloud Signs  Sudden reversal of wind direction  Noticeable increase in wind speed  Sudden drop in temperature

Possible weather: a. heavy rains (flash floods) b. lightning (forest fires) c. thunder (frightens animals) d. hail (crop damage) e. tornadoes f. strong, gusty winds Thunderstorm by Brainpop Thunderstorms

Lightning Storm Cumulonimbus cloud becomes electrically charged and ground below has opposite charge

current Lightning stroke: flow of current thru air (a poor conductor) from the – to the + cloud Lightning can flow from cloud to ground, cloud to cloud, and from ground to cloud glowing Bright light is caused by glowing air molecules heated by the current resistance Lightning follows the path of least resistance (easiest way to positive) easy Lightning rod offers lightning an easy, safe path to the ground (+)

Thunder Thunder is the shock wave caused by the explosive expansion of heated air 1100 Sound about 1100 ft/sec in air 5,280 ft in one mile seconds Distance from you to lightning = number of seconds between seeing the flash and hearing the thunder divided by 5. (5,280 ft / 1100 ft/sec = 5 seconds)

Types of Lightning Streak or bolt  Single or branched lines of light  Common in Puget Sound area

Sheet a. shapeless flash over wide area b. is cloud-to-cloud bolt hidden by the clouds c. common in Puget Sound area

Other types of lightning a. heat, ribbon, beaded (types of bolt) b. ball (only other shape lightning can have)

Tornado Tornado (a.k.a twister, cyclone) Counterclockwise column of rotating air extending from cumulonimbus cloud Per square foot, is the most destructive atmospheric event Rated by wind speed (F1 to F5) “Tornado season” = April, May, June Tornadoes that form over water are called “waterspouts”

Behavior of a tornado is unpredictable Typical tornado will: 1. Occur between 3-7 pm 2. Travel 4 miles 3. Be m wide 4. Travel mi/hour 5. Have wind speeds up to 300 mi/hr 6. Produce extremely low pressure 7. Be dark due to debris picked up Tornado by Brainpop

Lie flat in nearest ditch, etc. At home a. open windows, doors b. seek shelter in basement or under heavy table in middle of house On the trail of a tornado

Tropical Cyclone Nicknames 1. U.S.A.: hurricane 2. SE Asia, Japan: typhoon 3. Australia: willy-willy

Hurricane - Tropical Cyclone Rated by wind speed (category 1 to 5) Starts and grows over warm ocean water Composed of bands of thunderstorms spiraling counterclockwise around a low pressure center

Characteristics Several hundred miles wide Last many days (even weeks) Winds from mi/hr Contains an “eye”  Small region of low pressure  Surrounded by highest winds  Calm, peaceful, sunny weather  Last for about 1 hour as hurricane passes by Hurricances by Brainpop

Safety Rules Prepare for high winds Prepare for flooding (greatest source of damage)  Up to 20 in. of rain  Flooding by coastal water 3. Prepare for thunderstorms 4. Have on hand stored food, water, blankets, candles, matches, radio, etc. 5. Seek shelter HurricanesHurricanes Clip

(Relative) Humidity moisture Measure of the amount of moisture in the air compared to what the air could hold How “full” of water the air is Expressed as % saturated 100% relative humidity = saturated air

Relative Humidity Controlled by temperature Warm 1. Warm air holds more moisture than cool air (more space for water vapor between air molecules) warms decreases 2. As air warms, relative humidity decreases cools increases 3. As air cools, relative humidity increases Hygrometer is an instrument for measuring the humidity of the air or a gas.

What Factors Affect Weather & Climate?  The Sun  The Water Cycle  The Atmosphere  The Ocean

How Does the Sun Affect Weather? It warms the atmosphere & oceans It creates climate zones It keeps the water cycle going It affects weather patterns

Greenhouse effect. A phenomenon in which the atmosphere of a planet traps radiation emitted by its sun, caused by gases such as carbon dioxide, water vapor, and methane that allow incoming sunlight to pass through but retain heat radiated back from the planet's surface.

The Water Cycle All the water on the planet is recycled in this manner!

Parts of the Cycle Evaporation Evaporation—Water going from a liquid to a gas (gains energy from the sun)

Parts of the Cycle *Transpiration—evaporation of water from/out of plants. transpiration

Parts of the Cycle Condensation Condensation—Water going from a gas to a liquid (cools or loses energy) When this happens in the atmosphere, CLOUDS form.

Parts of the Cycle Precipitation—when water falls out the atmosphere. Forms when the water droplets in clouds become too heavy to stay up.

Precipitation Liquid water = rain Frozen water = snow or sleet or hail

The Water Cycle Water Cycle by Brainpop

Water Cycle Advanced by Brainpop

How does the atmosphere affect weather? The atmosphere is a mixture of gases that surrounds the Earth Has five different layers; each has different properties We’ll label them in just a minute… Air Temperature and Pressure change with altitude Weather occurs in the layer closest to Earth (troposphere)

Troposphere Stratosphere Mesosphere Ionosphere Exosphere Thermosphere Write in the labels! Ozone layer

Exosphere - the outermost layer of the Earth's atmosphere, where atmospheric pressure and temperature are low. Ionosphere - the atmospheric layer between the mesosphere and the exosphere; it is part of the thermosphere. Mesosphere - the atmospheric layer between the stratosphere and the ionosphere. Stratosphere - the atmospheric layer between the troposphere and the mesosphere. The stratosphere is characterized by a slight temperature increase with altitude and by the absence of clouds. Thermosphere - the layer of the atmosphere located above part of the ionosphere (starting at the coldest part of the atmosphere) and below outer space; it consists of the exosphere and part of the ionosphere. Troposphere - the lowest layer of the Earth's atmosphere. The weather and clouds occur in the troposphere.

Air Masses = body of air with a certain temperature and moisture level Can be warm or cold Can contain a lot of moisture or not a lot of moisture

Fronts = places where air masses meet 4 Types: Warm, Cold, Occluded, Stationary Each kind can bring different kinds of weather

Occluded Front:Stationary Front:

Science Saurus 221/222 & Reading a Weather Map Worksheet

Pressure – The force per unit area that one region of a gas, liquid, or solid exerts on another Compressed – reduction in volume – to get closer together Weight- the force of gravity on the object’s mass Altitude - the height of an object or point in relation to sea level or ground level.

Visibility – the degree of clearness (as of the atmosphere or ocean) Air pressure -pressure caused by the weight of the air above a given point Air Mass - a large body of air having characteristics of temperature, moisture, and pressure that are approximately uniform horizontally.

How does Air Pressure affect weather? How much the earth’s atmosphere is pressing down on us Measured with a BAROMETER If it CHANGES, then new weather is on the way: Falling Air Pressure = stormy weather coming Rising Air Pressure = fair weather coming Steady Air Pressure = no change is coming

Winds Winds = created from differences in air pressure Moves from areas of HIGH to LOW pressure Greater the difference in pressure, the FASTER the wind blows Measured with wind vanes and anemometers or you can estimate with the Beaufort Wind Scale ScienceSaurus 224/225

An anemometer is a device used for measuring wind speed, and is a common weather station instrument. A wind vane is a device that measures the direction of the wind.

Wind Speed is the speed/velocity of wind relative to the surface of the Earth Wind Direction is the direction the wind is blowing from. Wind blows from a source of high pressure to low pressure.

Beaufort Wind Scale

Global Winds Thousands of kilometers long; can cause weather to move in different directions Jet stream, prevailing westerlies, doldrums, horse latitudes, trade winds Big Winds Blowin’ Worksheet & Science Saurus Section 217

Global Winds Caused by the temperature difference in different regions Hot Tropical Regions—causes air to rise Cold polar Regions—causes air to sink

Global Winds Also affected by Earth’s Spin Coriolis Effect = causes winds to curve to the right in the N. Hemisphere; to the left in the S. Hemisphere

Big Winds Blowin’ Worksheet

Dew Point =Temperature at which the air is saturated (100% relative humidity) Several events can occur when the dew point temp. is reached: 1. If dew point temp. is above freezing: liquid a. water vapor condenses as liquid b. dew will form on surfaces

Dew Point c. cloud droplets will form in air 2. If dew point temp. is below freezing: a. water vapor condenses as a solid b. frost on surfaces c. snow (or hail) in the air

RainbowsRainbowsRainbowsRainbows sunshine Caused by sunshine on raindrops White light (all colors) is refracted (bent) into colors as it enters and exits the drop behind To see a rainbow you must have the sun behind you and raindrops in the air Diagram:

Rainbow by Brainpop

How does the Ocean affect weather? Ocean currents affect the temperature of the land they pass by Cold ocean currents = cooling effect Warm ocean currents = warming effect Temperature changes affect pressure – which then creates WINDS Winds blow this cooling or warming effect over the land no.mov

Climate Long-term behavior of atmosphere (100+ years) Large Large geographic area slow Very slow to change