Weather

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Weather
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Weather...

• You cant see me, but you feel me, you cant
  touch me, but I can touch you. I have been
  called the Breathe of the Gods, or the killer
  and giver of life, gentle and fierce, friendly
  and enemy, angry and happy. The Native Americans
  called me Moriah, and Snow Eater (Chinook). The
  Japanese call me Kaze and in Russia I am called
  Veter. I can shatter homes, or wake a child from
  a peaceful sleep or bring relief in times of
  need. I can spread the most dreaded diseases or
  bring a welcome freshness. What am I?

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Weather is....

• The current state of the atmosphere...what is
  happening right now

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Main points to remember as we learn about weather

• The sun warms the earths 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

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Weather Factors

• Weather The state of the atmosphere at a
  specific time and place
• TEMPERATURE
• the average motion of molecules
• ? TEMP ?movement of molecules feels hot
• ? TEMP ?movement of molecules feels cold

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Air Pressure

• Warm air expanding or rising air leaves behind
  L pressure
• Cold Airsinking air leaves an area of H pressure

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Wind Movement

• Uneven heating of the earths surface causes some
  areas to be warmer than others.
• As we know, warm always follows cold to share
  its warmth- when this happens in the atmosphere,
  wind happens!

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What causes winds?

• A wind is a horizontal movement of air from a
  area of high pressure to an area of low pressure
• It is this difference in pressure that makes the
  air movewind

• Winds are measured by direction and speed
• The anemometer is the tool we use to measure this
• Wind chill? cooling the wind causes

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Local 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!
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Land 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.

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Global Circulation and Wind Systems

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

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Global Winds

• Wind belts
• Horse Latitudes 30N and S of
  
• equator calm winds worlds
• desert areas
• Jet Streams 10km above the
• surface blow from the west to the east

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Intense heat Powerful CONVECTION

• Warm, moist air rises and leaves behind an area
  of low pressure. This is why most rain forests
  are found along equatorial regions.
• That air rises until it reaches the top of the
  troposphere, where it cant rise any further.
• It spreads out towards the polar regions HOT
  follows COLD wanting to share its warmth.
• As it spreads it begins to cool and sink-usually
  30N and S of the equator- sinking air produces
  an area of H pressure with dry conditions desert
  regions on earth

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

• Tradewinds
• Where do you think
• they got their name?
• Who were these winds
• particularly important to?

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

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

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Water in the Atmosphere Humidity

• Humidity measure of the amount of water vapor
  stuck between molecules in the air. The airs
  ability to hold water depends on the air temp
• The hotter the air, the more water the air can
  hold
• Cold air molecules move slower so droplets of
  water can start to stick togethercondensation
• Relative humidity the amount of water vapor()
  compared to the amount the air can hold- tool
  used is a psychrometer.
• 100air is saturated

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Cloud Formation

• Clouds form when water vapor condenses on dust,
  salt particles in the air
• The temperature in which condensation begins is
  called the dew point

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TYPES OF CLOUDS

• Cirrus Clouds wispy, feathery clouds

Form only at high levels, therefore are made of
ice crystals
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Types of Clouds

• Cumulus Clouds are puffy white cotton ball
  looking clouds

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Cumulonimbus Clouds

• These are thunderstorm clouds

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Types of Clouds

• Stratus Clouds clouds that form in flat layers-
  cover all or most of the sky and are low level
  clouds

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Air Masses

• Air masses are masses of air that have the same
  characteristics of the surface over which it
  develops
• Pressure Systems
• descending (going down)H pressure
• ascending (going up)L pressure

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Weather Foldable

• Warm front
• Cold front
• Occluded front
• Stationary Front

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Fronts the boundary between 2 air masses
This is the symbol on a map for a warm front

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

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Cold Fronts
This is the symbol for a cold front

• Cold air pushes under a warm air mass. Warm air
  rises quicklynarrow bands of violent storms form

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Occluded Front
This is the weather map symbol for an occluded
front

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

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Stationary Front
This is the weather map symbol for a stationary
front

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

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Reading a weather map

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

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Reading a weather map...

• Isotherm Connects areas of equal temperature
  therm means temperature

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Weather Station (not on the TV)