Weather

Bell Ringer: Day 1

In your science notebooks, make a heading for a new section of notes for our unit of study on WEATHER. 1.) Pretend that your younger cousin, Becky, asks you to tell her what weather is. In your notebook, define WEATHER in your own words

Bell Ringer

1. Hot air or water_____ a.) sinks b.) rises c.) does not move 2. What do we call the movement of hot water or air? convection

What IS weather?! (share answers from Bell Ringer)  Weather is “the state of the air and atmosphere at a particular time and place : the temperature, wind, moisture, and atmospheric pressure”.

Examples:  1.) The

weather

will be hot and dry today. 2.) The hikers took shelter from the

weather

cave.

in a small 3.) Make sure to check the

weather

before you pack for your trip.

* When you see the arrow symbol,  , you should be writing in your notes

Day 1: Introduction

What is the weather that we are experiencing in Bowling Green, KY today?

Using the chrome books, find a city in the United States that is having very different weather than we are today.

WHY???

1.) Now that we have heard about other cities, in the same country that we live in that have very different weather patterns than us, how can we explain the difference??

Weather patterns are complex, and very difficult to predict because weather is caused by so many different factors.

What causes weather?

The number one cause of weather is  uneven heating of the earth’s surface.

The uneven heating causes temperature differences, which in turn cause air currents (wind) to develop, which then move heat from where there is more heat (higher temperatures) to where there is less heat (lower temperatures).

HOT AIR (moves to)  COLD AIR

What do we call the movement of hot air?



CONVECTION

#1 cause of weather: uneven heating 

The atmosphere thus becomes a giant "heat engine", continuously driven by the sun.

High and low pressure areas, wind, clouds, and precipitation are all caused, either directly or indirectly, by this uneven heating and the resulting heat redistribution processes.



HEAT IS ENERGY, & WILL MOVE UNTIL EVERYTHING HAS THE SAME AMOUNT OF ENERGY, OR IS THE SAME TEMPERATURE

Advanced: Going Into More Detail

Two main modes of this heat redistribution: (1) VERTICAL heat transport: Solar heating of the Earth's surface makes the atmosphere convectively unstable , causing vertical air currents to develop. This is what causes puffy-looking clouds, showers, and thunderstorms to form in warm air masses.

(2) HORIZONTAL heat transport: Because the Earth is a sphere, it receives more sunlight in the tropics, and less sunlight toward the North and South Poles. This causes horizontal temperature differences to develop, which in turn causes air pressure differences, leading to wind that transports heat from the tropics to the high latitudes.

Together, this uneven heating in both the horizontal and vertical directions in the atmosphere causes everything that we perceive as "weather".

What causes weather?

 Another factor that causes weather is WATER.

 During the water cycle, heat energy is constantly causing water to change states.

List the 3 states of water: & put a + over the state with the most energy, and a – over the state with the least amount of energy The energy changes during the water cycle cause weather.

CLOUDS & PRECIPITATION



Wind flowing over the Earth's surface causes evaporation of surface water.

Does water evaporating gain or lose energy?

Evaporation requires heat (water gains energy)

How would water evaporating affect the temperature of the earth’s surface?

CLOUDS & PRECIPITATION

Water evaporating would cool the surface of the earth.

Where does water go when its evaporated from earth’s surface?

After evaporating, water releases that heat higher up in the atmosphere when the water vapor condenses to form clouds and precipitation.

Advanced FYI: This primary mode of vertical heat transport is called "moist convection".

Diagram of how water can cause weather: In your packet, draw this diagram, and label the following: 1. evaporation & water gains energy, 2. surface cools, 3. condensation releases heat energy

The following photo from the Space Station shows a large thunderstorm , which represents moist convection transporting heat from the lower to the upper atmosphere:

What causes weather?

Now that we have seen an example of how water affects weather, we need to know some important terms: 1. Humidity = the amount of water vapor or moisture in the air 2. Relative Humidity = is the amount of moisture in the air compared to what the air can "hold" at that temperature

Humidity

How does humidity cause or affect weather?

Air Pressure & Air Masses

The two causes of weather that we have learned about are : uneven heating of the earth’s surface, & water.

Now, we will learn how meteorologists combine these two causes to predict weather.

Have you ever wondered how a day could begin warm, and you could wear shorts in the morning, and by the evening you need a heavy coat???

Air Masses!

 Changes in weather are caused by the movement and interaction of air masses.

Hot, Dry Air + Cold, Moist Air = WEATHER!

Two main characteristics define air masses:



1.) Temperature



2.) Moisture content

The temperature and moisture content of air masses are abbreviated as two letters. The first letter is a lower case letter and is used to symbolize the overall moisture in the air. The second letter (capitalized), symbolizes the temperature.

Example of air mass

One example of an air mass

: continental tropical (

cT

) The air mass symbol “cT” tells scientists that the air is:

c = continental

, or formed over land, so it has less moisture than air formed over water.

T = Tropical

, or formed in a warm area (close to equator)

4 Types of Air

• • • • continental air -

c

maritime air -

m

Tropical air -

T

Polar air -

P Based on the names (above), can you describe each of the types of air ?

Types of Air

• continental air

c=

Any body of air that forms over a large land area and has low moisture.

• maritime air

m =

Air that forms over a large body of water and is usually moist. Also called “oceanic air”. Maritime air masses are unique because they usually stay the same & resist change! Why do you think that is?

Tropical air

T =

air formed in regions where the temperature is warm. A tropical air mass tells us the air is warm and formed in the lower latitudes (close to the equator).

• Polar air

P = air formed in regions where the temperature is colder.

1.) Compared to tropical air, where do you think Polar air forms?

2.) Pause for a moment, & identify the opposite of each type of air.

3.) Why are Tropical (T) & Polar (P) air capitalized, while Maritime (m) & Continental (c) are lower case?

Opposite Air Masses

Continental (formed over land) ,

opposite of

Maritime (formed over water)

Maritime is AKA (also known as) “Maritime front”, “MAMS”, or “oceanic air mass”

Tropical (is hot or warm)

, opposite of

Polar (cold)

Air masses: Types of Air:

• • • • continental air -

c

maritime air -

m

Tropical air -

T

Polar air -

P

• maritime tropical (

mT

) • continental tropical (

cT

) • maritime polar (

mP

) • maritime tropical (

cP

)

1. maritime Tropical (

mT

) 2. continental Tropical (

cT

) 3. maritime Polar (

mP

) 4. continental Polar (

cP

) 1. Moist & Warm 2. Dry & Warm 3. Moist & Cold 4. Dry & Cold

Scientists sometimes need a more extreme description for VERY cold air…& they call it “Arctic” air instead of Polar.

What type of air mass would this be?

Can you guess what type of air forms off the north west coast of the U.S.A., by the state of Washington & Canada?

Which types of Air Mass it will be is determined by where the air mass comes from; not where it travels to.

What type of air mass would form here?

What type of air mass would form here?

Atmosphere Definition

The layer of gases surrounding Earth; composed mainly of nitrogen and oxygen 78% nitrogen 21% oxygen 1% other

Layers

http://www.fi.edu/wright/again/wings.avkids.com/wings.avkids.com/Book/Atmosphere/Images/atmos_layers.gif

Troposphere

• Where all plants and animals live and breathe • Where weather takes place • 90% of the mass of the atmosphere • Thinnest layer • Temp decreases with altitude http://atschool.eduweb.co.uk/kingworc/departments/geography/nottingham/atmosphere/pages/gfx/troposphere.jpg

Stratosphere

• Ozone in this layer stops many of the sun's harmful rays from reaching the earth • People can not breathe in this layer. • Temperature increases as altitude increases • Keeps air warm and protects life on Earth

Ozone Layer

•Pale blue gas with a strong odor.

•90% of all ozone is found in the stratosphere •10% is found in the troposphere •

Ozone is extremely important because it is the only gas that absorbs ultraviolet radiation from the Sun and protects the surface of the Earth and people from the damaging effects of UV rays

http://ess.geology.ufl.edu/ess/Notes/090-Ozone_Depletion/depl2.jpg

Mesosphere

• Meso = middle between strato and thermo • Windstorms reach speeds of 320 km/h • Temp decreases with altitude – coldest layer (-93 degrees C) • This is where we see "falling stars" – meteors burning up as they fall to Earth

Ionosphere

• An extension or a part of the upper mesosphere and lower thermosphere.

So technically, the ionosphere is not another atmospheric layer.

• Composed of electrically charged particles • Auroras take place in this area • Radio waves are reflected by this layer

Thermosphere

• Layer of the atmosphere which is first exposed to the Sun's radiation • Temperatures are very high, but doesn’t feel hot because particles don’t transfer energy • The air is very thin

Exosphere

• Highest layer of the atmosphere. The air is very thin here • Atoms and molecules escape into space

Let’s look at an animation:

http://earthguide.ucsd.edu/earthgu ide/diagrams/atmosphere/index.ht

ml

Air Pressure

HIGH AND LOW PRESSURE AREAS

•

Uneven heating of the earth’s surface causes high and low pressure areas to develop.

•

Wind is caused by air flowing from an area of high pressure to an area of low pressure.

Wind’s direction is influenced by earth’s rotation, which makes things complicated!!!

HIGH  LOW

Wind wants to flow from high to low pressure areas, but the rotation of the earth prevents this

• So, instead, wind flows AROUND areas of high and low pressure. • Clockwise around high pressure, counter clockwise around low pressure • The diverting effect of earth’s rotation is called the Coriolis effect

Advanced FYI

•

The horizontal transport of heat by wind from low (equator) to high latitudes (like Greenland) is strongly influenced by the Earth's rotation, which prevents the wind from flowing directly from high pressure to low pressure, and instead causes the wind to flow around high and low pressure centers.

Coriolis Effect

•

The following example shows how the wind flows in the Northern Hemisphere...in the Southern Hemisphere, the wind flows in the opposite direction around high and low pressure areas.

• •

This diverting force is called the "Coriolis effect". The spiral shape of cloud systems can be clearly seen from space, such as in this famous photo taken by Apollo 17 astronaut Harrison Schmitt, and is evidence of the Coriolis effect.

• •

I want students to use DE to get this info….

How Does the Movement of Air Masses Affect Weather? (fronts)

Meteorologists focus a great deal on the study ofweather patterns known as fronts. Fronts are the boundaries between large masses of air. Airmasses form over large areas of Earth’s surface and take on the general temperature and moisture characteristics of the area over which they form. As an air mass moves across a region, the location of a front will change. Air masses are generally defined by their overall temperature andair pressure. As these air masses move and collide with one another, different types ofweather can occur along a front.

Advanced: Big Picture

•

All of these horizontal and vertical heat transport processes produce complete atmospheric circulation "cells". This is a consequence of the fact that for all of the air transporting heat from higher to lower temperatures, there must also be a return flow of air in the opposite direction.

Advanced: Big Picture

•

For instance, for all of the air rapidly rising within a thunderstorm, there must be an equal amount of air sinking elsewhere. This sinking occurs over a much broader area than the strong updrafts in the thunderstorm, and the rate of sinking is more slower. This is why you feel turbulence when flying through clouds, but not so much in the clear areas around the clouds. The distances involved in the circulation cells is typically tens of miles.

General: Big Picture

The movement of air from areas of high to low pressure forms atmospheric circulation cells.

Conclusion (adv & gen)

•

So, when you experience a clear day without a cloud in the sky, you are in the descending branch of an atmospheric circulation cell. That descending air is being forced downward by rising air in precipitation systems hundreds or even thousands of miles away. Then, because these circulation cells tend to travel, in a day or two you find yourself in the ascending branch of a circulation cell, with clouds and rain (or snow).

If all this sounds complicated, that's because it is. But remember, all of this complexity we experience as "weather" is ultimately the result of uneven heating of the Earth by the sun, and the atmosphere continuously 'trying' to reduce the resulting differences in temperature.