Weather: The condition of the air that surrounds the Earth

··Develops in the atmosphere (atmosphere is the first 100 miles above the Earth)
Weather occurs in the troposphere (lower level) about 6-10 miles up

··The atmosphere is in constant disequilibrium because of uneven heating of the Earth's surface. -- remember direct/i indirect heating experiment

··Because of various laws of physics, the Earth is in a coutinuous attempt to reach equilibrium (where the temperature and other conditions are constant everywhere). This will never happen!--- explain
--causes of this disequilibrium
a. sun
b. air movement
c. spinning of earth
d. oceans (how)
e. uneven heating

··Water heats and cools slowly, land quickly causing different pockes of warm and cool air that are continuously moving trying to reach equilibrium. (remember experiment)

··We must have these weather occurrances in order to make our planet inhabitable. (Remember the video: "Weather Class")

FOUR ELEMENTS OF WEATHER-- (We log them in)
-- make concept map of these elements--

A. Temperature or heat
B. Air movement or wind
C. Moisture
D. Air presssure

A. Temperature-- degree of heat in the atmosphere
measured by thermometer
comes from the sun
----1/2 billionth of sun's heat enters our atmosphere
--- 93, 000, 000 miles away-- 5,000 degrees surface temp
--- the sun drives our weather-- remember the disequilibrium?

1/3 sun's heat reflected back
1/5 heats air
1/2 warms Earth, which in turn warms the air

Ways that the sun heats the Earth

Conduction--- discuss
Radiation --- discuss
Convection-- warm air moves up, cool air moves down-- discuss

B. Air Movement (Wind)
air moves from high pressure to low pressure
remember the "Weather Class" example of water running down hill?
the greater the difference of pressure, the greater the wind speed.
Named from the direction it blows (north wind, etc) -- we log that in--

Coriolis Effect-----global winds

It doesn't blow in a straight line because of the spinning of the Earth.
This is called the Coriolis effect. see page 499 in book

Appears to curve right in Northern Hemisphere and left in Southern Hemisphere

**Equator to 30 degrees north====> Easterlies (Trade Winds)

**30 degrees north to 60 degrees north =====> Westerlies

look what hurricanes from the Atlantic do. When they get to the Southern USA, they often turn and go back out to sea. This is because of the prevailing west winds above 30 degrees north

**60 degrees north polar easterlies--

Same in the south.

From which direction do our prevailing winds come? From which direction does our weather come?

Local winds----
caused by convection--- hot air rises, cool air falls

Sea breeze and Land breeze

Sea breeze
During the day at the lake-- land heats quicker than water, (remember our experiment?) so air above land heats more quickly and rises, allowing low pressure area for air above the water to move into land. It is usually cooler and feels good on a hot day.

Land breeze
At night at the lake-- land cools more quickly than water (again, remember our experiment?) so air above the water is warmer than above land. It rises allowing low pressure are for air above land to move out to "sea"

These winds are caused by the process called Convection.

C. Air presssure-- weight of the air in the atmosphere
Evangelista Toricelli proved that air has weight
Measured by a barometer

We are walking around under an ocean of air
We are used to the weight of the air on our bodies

Warm air weighs less= lower pressure
Cool air weighs more = high pressure

What is the approximate barometric pressure? (30 inches)

High pressure keeps moisture down---- sunny skies---fair weather, usually
Low pressure alows moisture to rise---- cloudy skies

What happens when the barometric pressure drops
tornadoes down in the mid 28's-- hurricanes (tropical depressions-- areas of low)

What does the pressure do during a storm go up or go down?

Go to Weather Underground website for Emporia/Council Grove and find the history of some of the days.

Find a day when the pressure dropped significantly--
What do the conditions do
Find more examples
Write up what you discovered

D. Moisture--water vapor
from evaporation-- water holds its heat (remember the soil/water experiment?)
Moisture comes mostly from the oceans-- they help drive our weather

Amount of moisture in the air= humidity
Measured with a hygrometer.
Saturation--- when air is holding all of the water it is capable of holding

temperature air reaches saturation is called DEW POINT (we log that in)
Does air pressure effect the amount of moisture in the air?--- yes
remember that low pressure allows water vapor to rise into the sky

What is heavier, moist air or dry air?

Experiment tomorrow!

Question:

Info Gathering:

Hypothesis

(need to write up wet/dry air experiment)

water molecule vs oxygen molecule

girls = hydrogen
boys = oxygen

use examples

a certain number of molecules are contained within any "box" of air. Doesn't matter whether water vapor or air vapor the same number are present.

What is heavier wet or dry air?