WEATHER: HAPPENS WHETHER YOU LIKE IT OR NOT.part+1... · WEATHER: HAPPENS WHETHER YOU LIKE IT OR NOT. ... Dry Adiabatic Lapse Rate Moist Adiabatic Lapse Rate . ... Dew point temperature

WEATHER: HAPPENS WHETHER

YOU LIKE IT OR NOT. Part 1 Parts of the atmosphere, what makes weather, and weather symbols

Part 2 Severe weather types and how humans should react.

1

PARTS OF THE ATMOSPHERE

Identify two spheres and what features helped identify each sphere

Layers of the Earth's Atmosphere

• Five layers

– Exosphere

– Thermosphere

– Mesosphere

– Stratosphere

– Troposphere

Layers of the Earth's Atmosphere

• 1) Troposphere -contains half of the Earth's atmosphere. Weather occurs in this layer.

Layers of the Earth's Atmosphere

• 2) Stratosphere - many jet aircrafts fly here because it is very stable. The ozone layer absorbs harmful rays from the Sun.

http://www.youtube.com/watch?v=FHtvDA0W34I

Layers of the Earth's Atmosphere

• 3) Meteors or rock fragments burn up in the mesosphere.

http://www.youtube.com/watch?v=90Omh7_I8vI

Layers of the Earth's Atmosphere

• 4) The thermosphere is a layer with auroras. Where the space shuttle orbits.

– An aurora is a natural light display caused by the collision of energetic charged particles with atoms in the thermosphere.

red and green

auroras in Alaska

• Aurora from the International Space Station

Layers of the Earth's Atmosphere

Layers of the Earth's Atmosphere

• 5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

Why does the temperature change?

Oxygen and other elements in the upper atmosphere absorb energy and do not have many particles to run into to loose kinetic energy. Ozone layer in the stratosphere heats up the atmosphere as the ozone absorbs UV radiation. The stratopause is the upper limit of the ozone layer. Warm air rises in the troposphere until it cools off when it reaches the tropopause then sinks back toward the ground.

Why is the sky blue?

From NASA: • Like energy passing through the ocean, light energy

travels in waves, too. Some light travels in short, "choppy" waves. Other light travels in long, lazy waves. Bluelight waves are shorter than red light waves.

• All light travels in a straight line unless something gets in the way to—

• reflect it (like a mirror) • bend it (like a prism) • or scatter it (like molecules of the gases in the

atmosphere)

Why is the sky blue?

From NASA: Sunlight reaches Earth's atmosphere and is scattered in all directions

by all the gases and particles in the air. Blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.

Why is the sky blue?

From NASA:

As the Sun gets lower in the sky, its light is passing through more of the atmosphere to reach you. Even more of the blue light is scattered, allowing the reds and yellows to pass straight through to your eyes.

http://www.youtube.com/watch?feature=player_detailpage&v=-yrZpTHBEss#t=165s

What is a cloud?

• What are clouds? A cloud is a large collection of very tiny droplets of water or ice crystals. The droplets are so small and light that they can float in the air. How are clouds formed? All air contains water, but near the ground it is usually in the form of an invisible gas called water vapor. When warm air rises, it expands and cools. Cool air can't hold as much water vapor as warm air, so some of the vapor condenses onto tiny pieces of dust that are floating in the air and forms a tiny droplet around each dust particle. When billions of these droplets come together they become a visible cloud.

Types of Clouds

• High clouds

– Cirrus, cirrostratus, cirrocumulus

– Often made up of ice crystals

– Not precipitation makers

• Middle clouds

– Prefix alto-

– Light snow or drizzle

Types of Clouds

• Low clouds – Stratus – light precipitation

– Nimbostratus – stable air, precipitation maker

– Stratocumulus – scalloped bottom

• Clouds of vertical development – Some clouds extend upward from mid to high

altitude

– Assoc w/unstable air

– Cumulonimbus – T storms

Types of Clouds

What is it?

What is it?

What is it?

Types of Clouds

• http://www.youtube.com/watch?v=375S1hIDAvs

• http://www.youtube.com/watch?feature=player_detailpage&v=6ODJA1tIWOA#t=45s

FOUR INGREDIENTS OF WEATHER

Def: Parcel = A blob of air we can identify as it moves through the atmos Def: Environment = the air outside of the parcel Def: Adiabatic Process = no mixing of the air in the environment with the air in the parcel KEY IDEA:

1st Ingredient: An Unstable Atmosphere

Def. Stability: Resistance to change

Compare the temp of the parcel to the temp of the environment

parcel

Rising Air and Stability.

LCL

LFC

EL

For an air parcel… Rising air _________ by __________. Sinking air _________ by __________

cools expansion

warms compression

= 10°C/km

Temperature of a parcel with RH<100% cools at this rate when it ascends and warms at this rate when it descends

Temperature of a parcel with RH=100% cools at this rate when it ascends (only applies to ascending parcels of air)

= 6°C/km

How much does its temperature change?

Dry Adiabatic Lapse Rate Moist Adiabatic Lapse Rate

http://www.youtube.com/watch?v=p3PNSp7E4Rw

2nd Ingredient – Lifting mechanism

Trigger Mechanism:

- - - - -

Anything that can cause the air to rise

Surface convergence = when air flows into the same area from different directions. Some air is forced upward.

Fronts = collisions between air masses

Orographic lift (air forced to rise by a mountain)

Sea Breeze

Rising Thermals of warm air

Trigger Mechanism – Orographic lift

COOL

COOL

COOL

COOL

HOT

High Pressure

High Pressure

Low Pressure

Trigger Mechanism – Rising Thermals of Air

3rd Ingredient –Surface Moisture

*** Fuel for the storm is warm moist air Td at least 60°F energy source = the production of cloud (condensation) releases latent heat

Moisture Supply Primary: Gulf of Mexico Secondary: Evapotranspiration from the soil and vegetation

Dry

Ordinary Thunderstorms

Updraft: warm moist air that rises cools condensation = clouds

D O W N D R A F T

Downdraft: mixing in of dry air causes evaporation = cooling precipitation falls and drags the air downward The result: cold dense pocket of rapidly descending air loaded with precip

Anvil

Tropopause

Updraft is not separated from the downdraft Kills the storm!

Rarely severe. It lasts less than 1 hour

U P D R A F T

updraft downdraft

Severe vs. Non-severe: The 4th ingredient

Role of wind shear: Where to find wind shear:

No wind shear Great Wind Shear

Surface

Tropopause

Surface

Tropopause

To separate the updraft from the downdraft

On a sounding – the winds are on the right hand side

Winds do not increase with height

(no shear) Winds do increase with height (lots of shear)

Wind shear – change in wind speed and direction with height

National Weather Service Criteria for SEVERE STORMS: Just need one of the three conditions below…

Wind - 50 kts (58 mph) Hail - 1” or greater Tornado

Weather Watch (tornado)

Conditions favorable for tornado production (severe weather)

1. Adequate Surface moisture

– Dew point more than 60 F

2. Lifting mechanism

3. Unstable Atmosphere

4. Wind Shear

– Change speed and direction

Tornado Watch Box -four ingredients needed to produce severe weather all occur

inside

How big was the largest hail stone ever found?

A. 10 inches in circumference (soft ball size)

B. 18 inches in circumference (cantaloupe size)

C. 28 inches in circumference (basketball size)

D. 38 inches in circumference (small beach ball size)

How wide was the widest tornado ever observed? A.½ a mile wide B.1 mile wide C.1 ½ miles wide D.2 miles wide E.2 ½ miles wide

Take a guess:

FRONTS

AIR MASS

Defined : A large body of air (hundreds of miles in

extent) in which temperature and moisture are

relatively uniform

ELEMENTS OF AN AIR MASS

Temperature - determined by the latitude of the

source region

Moisture content - determined by the type of

surface over which the air mass developed. When air stagnates over the snow-covered polar latitude continents in winter, the

near surface air rapidly loses heat through radiation during the long winter nights.

Although the entire air column can cool, the greatest cooling occurs near the

surface.

In the tropics and subtropics, the intense sunlight heats the surface during the day.

The air immediately above the surface is heated upon contact.

AIR MASS CLASSIFICATION

AIR MASSES THAT AFFECT US

Continental Polar

Cold temp, little moisture

Originate over Canadian plains

Maritime Tropical

Warm temp, lots of moisture

Originate over tropical waters

and Gulf of Mexico

FRONTS

The boundaries between air masses of different densities.

Fronts are classified as to which type of air mass (cold or warm) is replacing the other.

Fronts extend not only in the horizontal direction, but in the vertical as well. Therefore, when referring to the frontal surface (or frontal zone), we referring to both the horizontal and vertical components of the front

MOVEMENT OF AIR

When two air masses collide, less dense air rises

over more dense air.

As air rises, it cools. The cooling process can create

clouds, and eventually precipitation.

PRECIPITATION – COLD FRONTS

Cold air pushes warm air up

A more abrupt change in cloud cover

Forms narrow bands of taller clouds AT the cold front

PRECIPITATION – WARM FRONTS

Warm air goes

over the top of

cold air

A gradual change

in cloud cover

Forms wider

bands of shorter

clouds BEFORE

the warm front

http://www.youtube.com/watch?feature=player_detailpage&v=QQ-AOCYnJrY#t=95s http://www.youtube.com/watch?feature=player_detailpage&v=Ak9CBB1bTcc#t=42s http://www.youtube.com/watch?v=msSVQ903T8k

WEATHER SYMBOLS

Weather Symbols

Wind

Pressure trend

Sky Cover

Dew Point

Weather

Temperature

The Station Model

The weather of an individual weather station is plotted on a station model.

Temperature: is defined as a measure of the average of the speed of the molecules in motion in the air. - fast the molecules = high temperatures - slow molecules = low temperatues

The value highlighted in yellow located in the upper left corner is the temperature in degrees Fahrenheit.

Weather Symbol

The weather symbol indicates the type of weather occurring at the time the observation is taken.

The higher the dew points, the higher the moisture content in the air.

Dew point = the temperature to which the air would have to cool in order to reach saturation.

Saturation = When the dew point temperature and air temperature are equal. You can tell if air is saturated by the formation of water droplets (drops on a glass).

Dew point temperature is NEVER GREATER than the air temperature.

What do you think happens when the temperature equals the dew point?

Dew Point Temperature

Indicates the amount of moisture in the air

Formation of droplets of water, fog, or precipitation.

Cloud Cover

Air Pressure The value highlighted in yellow represents the last three digits of the observed pressure reading in millibars (mb).

Wind barbs point in the direction "from" which the wind is blowing. In the case of the diagram to the right, the orientation of the wind barb indicates winds from the Northeast.

Wind speed is given here in the units of "knots". A "Knot" is a nautical mile per hour.

Each short barb represents 5 knots, each long barb 10 knots. A long barb and a short barb is 15 knots, simply by adding the value of each barb together (10 knots + 5 knots = 15 knots).

If only a station circle is plotted, the winds are calm.