Weather is....Weather is....

Weather is the day-to-day state of Weather is the day-to-day state of the atmosphere, and its short-term the atmosphere, and its short-term (minutes to weeks) variation(minutes to weeks) variation

Weather includes sunshine, rain, Weather includes sunshine, rain, cloud cover, winds, hail, snow, cloud cover, winds, hail, snow, sleet, freezing rain, flooding, sleet, freezing rain, flooding, blizzards, ice storms, blizzards, ice storms, thunderstorms, steady rains from a thunderstorms, steady rains from a cold front or warm front, excessive cold front or warm front, excessive heat, heat waves and moreheat, heat waves and more

Climate is....Climate is....

statistical weather information that statistical weather information that describes the variation of weather describes the variation of weather at a given place for a specified at a given place for a specified intervalinterval

Climate may include precipitation, Climate may include precipitation, temperature, humidity, sunshine, temperature, humidity, sunshine, wind velocity, phenomena such as wind velocity, phenomena such as fog, frost, and hail storms over a fog, frost, and hail storms over a long period of time.long period of time.

Weather vs. Climate in NCWeather vs. Climate in NC

ClimateClimate

North Carolina has a humid, subtropical climate. Winters are short and mild, while summers are usually very sultry; spring and fall are distinct and refreshing periods of transition. In most of North Carolina, temperatures rarely go above 100°F (38°C) or fall below 10°F (–12°C)

WeatherWeather

Monday morning:Sunny in the morning...Then becoming partly sunny. Highs in the lower 70s. East winds around 5 mph

Monday evening:Partly cloudy. Lows in the upper 40s. Light and variable winds...Becoming east around 5 mph after midnight.

Main points to remember as we learn about weather:

The sun warms the earth’s surface and therefore all the air above the surface

The earth is warmed most at the equator and least at the poles---why?

The air above land is warmed more quickly than air above water.

Warm air expands and rises, creating an area of low pressure; cold air is dense and sinks, creating an area of high pressure

Air MassAir Mass

• large body of air that has similar temperature and humidity properties throughout • Properties of air masses, however are modified as they move over areas outside where they originate • Source regions = regions where air masses develop their characteristics– need large areas with similar characteristic

Air Mass ClassificationAir Mass Classification

Air masses have 4 major classificationsAir masses have 4 major classifications

• Polar (P)

• Tropical (T)

• continental (c) or maritime (m)

• Arctic (A) - extremely cold air masses

Air Mass ClassificationAir Mass Classification

Air masses are classified according to their source regions:

1.Warm and dry continental tropical2.Warm and humid maritime tropical3. Cold and dry continental polar4. Cold and humid maritime polar5. Arctic

All five of these can be found in North America

Air MassesAir Masses

• Air masses are masses of air that have the same characteristics of the surface over which it develops

Wind SystemsWind Systems

Air flows from areas of HIGH pressure to areas of LOW pressure; this creates wind

Winds are named for the direction from which they flow. • Easterlies flow from the East to the West

Jet StreamJet Stream

A high altitude, narrow, westerly wind band that occurs above large temperature contrasts and can flow as fast as 185 km/h.

Coriolis EffectCoriolis Effect

• Caused by the Earth’s rotation

• Pulls the wind to the right in the northern hemisphere

• Pulls the wind to the left in the southern hemisphere

• Strongest at the Poles

• None at the Equator

Example of Coriolis EffectExample of Coriolis Effect

http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm

Air Pressure

Warm air= expanding or rising air= leaves behind L pressure

Cold Air=sinking air= leaves an area of H pressure

Air Pressure/Atmospheric Pressure is measured with a barometer

Wind MovementWind Movement Uneven heating of Uneven heating of

the earth’s surface the earth’s surface causes some areas causes some areas to be warmer than to be warmer than others.others.

As we know, warm As we know, warm always follows cold always follows cold to share it’s warmth- to share it’s warmth- when this happens in when this happens in the atmosphere, the atmosphere, wind happens!wind happens!

What causes winds? A wind is a A wind is a

horizontal horizontal movement of air movement of air from a area of from a area of high pressure to high pressure to an area of low an area of low pressurepressure

It is this It is this difference in difference in pressure that pressure that makes the air makes the air move=windmove=wind

Winds are measured by direction and speed

The anemometer is the tool we use to measure this

Wind chill=↑ cooling the wind causes

Local WindsLocal Winds The land cools and heats faster than the

ocean. Water holds heat longer than land, and takes longer to heat or cool.

SEA BREEZE During the day, the land gets hotter faster than the water. The heated air rises, leaving behind an area of low pressure. Wind from the cooler sea blows in to take the place of that warmer air. These happen during the day!

Land BreezesLand Breezes At night the lands cools off faster

than the sea. Cool air sinks creating an area of high pressure. Wind blows from the land to the sea.

STOPSTOP

Global Circulation and Global Circulation and Wind SystemsWind Systems

Solar energy is at its Solar energy is at its greatest around the greatest around the equator---Why?equator---Why?

Global Winds:

Wind belts: Horse Latitudes= 30°N and S of

equator =calm winds= worlds desert areas Jet Streams= 10km above the surface blow from the west to the

east

Some of the air moves back towards the equator as it sinks...

Tradewinds: Where do you thinkthey got their name?

Who were these winds

particularly important to?

There was an area that sailors There was an area that sailors avoided with their lives...avoided with their lives...

THE DOLDRUMS... THE DOLDRUMS... is the area around is the area around the equator the equator where the wind where the wind completely dies completely dies out... which out... which meant death as meant death as soon as the fresh soon as the fresh water ran out.water ran out.

Weather Foldable

Warm front Cold front Occluded front Stationary Front

Fronts: the boundary between 2 air masses

Warm Front: warm air slides over departing cold air- large bands of precipitation form

This is the symbol on a map for a warm front

Cold Fronts

Cold air pushes under a warm air mass. Warm air rises quickly=narrow bands of violent storms form

This is the symbol for a cold front

Occluded Front

2 air masses merge and force warm air between them to rise quickly. Strong winds and heavy precipitation will occur

This is the weather map symbol for an occluded front

Stationary Front

Warm or cold front stops moving. Light wind and precipitation may occur across the front boundary

This is the weather map symbol for a stationary front

Reading a weather map

ISOBAR= connects areas of equal pressure BAR comes from BARometric pressure

Reading a weather map...

Isotherm: Connects areas of equal temperature; therm means temperature