Download Weather vs Climate-Chapter 17 Atmosphere

Weather vs Climate-Chapter 17.1 Atmosphere.
Weather- the state of the atmosphere given time and place is known as weather.
The combinations of Earth’s motion and energy from the sun produce a variety of weather.
Climate
 is based on observations of weather that have been collected over many years.
 It helps describe a place or region.
 It is Average weather.
Properties of weather and climate
 Air temp, humidity, type, and amount of precipitation
Earth is 4.6 billion years old
 Atmosphere- starts as gases that were emitted during volcanic eruptions.
 O2 accumulates 2.5 billion years ago.
 Atmosphere- continues to exchange materials with ocean and life on Earth.
Major Components of Atmosphere
 Air is a mixture of different gases and particles each with its own different properties.
 The composition of air varies from time to time and place to place.
 99% of clean dry air is 2 gases
o Nitrogen
o Oxygen
Variable Components of Air (Pg477)
Important materials that have significant effects on weather and climate.
 Water vapor varies from almost none to 4% .
1. it is the source of all clouds and precipitation
2. it absorbs heat given off by Earth
3. absorbs some solar energy
 Dust particles
1. a large quantity of solid and liquid particles are suspended with in the air.
2. Visible dust is too heavy to stay in the air for too long
3. microscopic dust remains suspended for longer periods of time
 Sea salt from breaking waves
 Fine soil blown in the air
 Smoke and soot from fires
 Wind lifts
1. Pollen and microorganisms
2. Ash and dust from volcanic eruptions.
 Ozone Pg (478)
1. is a form of oxygen that combines 3 oxygen atoms into each molecule
2. not the same as the oxygen we breathe
3. very little ozone in the atmosphere and not distributed evenly
4. concentrated in layer located between 10&50 kilometers above Earth’s surface
where there are enough molecules to bring about the required collisions.
5. formed when O2 is split when they absorb ultraviolet (UV) radiation emitted by
the sun.
6. the single oxygen atom collides with O2 in the presence of a third neutral
molecule that acts as a catalyst.
7. is important because it absorbs potentially harmful UV radiation from the sun that
would normally make the Earth uninhabitable
Human influence PG 478
1. Air pollutants are airborne particles and gases that occur in concentrations large enough to
endanger the health of organism
2. Primary pollutants-emissions for transportation vehicle account for nearly half the primary
pollutants by weight.
3. Secondary emissions are not emitted directly in to the air, they form when reactions take place
among primary pollutants and other substances in the air.
4. Photochemical reactions are reactions triggered by strong sunlight. Example- gases and particles
make photochemical smog.
Height and Structure of the Atmosphere Pg 479
Where does the atmosphere end and outer space begin? There is no sharp boundary.
The atmosphere thins as you travel away from Earth until there are too few gas molecules to detect.
 Pressure changes-atmosphere pressure is the weight of air above.
 Temperature Changes as elevation changes.
 The atmosphere can be divided vertically into four layer based on temperature.
1. Troposphere Pg 480 bottom layer where weather occurs. Up to approx 20km
i.Thickness varies with latitude and season
ii.Temperature drops as altitude increases at 12 kilometers
2. Stratosphere- temperature remains constant to a height of about 20 km then the
temperature increases because of the concentrated ozone which will absorb ultraviolet
radiation for the sun. from 20km to approx 50 km.
3. Mesosphere-temperature decreases with height. Continues upward with no well
defined upper limit. Approx 50-85km
4. Thermosphere-contains only a fraction of the atmosphere’s mass and temperature
increases in the thermosphere because oxygen and nitrogen absorb short-wave, highenergy solar radiation. 90 km and upward
Earth-Sun Relationships-Nearly all of the energy that drives Earth’s variable weather and climate
come from the sun. Earth absorbs only a tiny percentage of the energy from the sun.
 The amount of solar energy received varies
1. with latitude
2. time of day
3. season of the day
 variations in solar heating are caused by
1. the motion of Earth relative to the sun
2. variations in land and ocean surfaces
It is the unequal heating of Earth that creates winds and drives the ocean’s currents. Theses movements
transport heat from the tropics towards the poles in attempt to balance energy difference. The results of
these processes are the phenomena known as WEATHER.
Earths Motions
 rotation-spinning of Earth about it axis ( an imaginary line running from the north pole to the
south pole)
 revolution-is the movement of Earth in its orbit around the sun which is elliptical
Earth’s Orientation-Seasonal changes occur because Earth’s position relative to the sun continually
changes as it travels along its orbit.
 Why is it colder in winter than summer?
1. length of day
2. gradual change in the angle of the noon sun above the horizon affect the amount of energy
Earth receives
3. Earth’s axis is not perpendicular to the plane of it orbit around the sun.
o It is tilted 23.5 degrees from the perpendicular.
o The axis always points toward the North Star as it revolves around the sun.
o The position of Earth’s axis to the sun’s rays is constantly changing and this is why
we have seasonal changes.
o Noon sun varies by up to 47 degrees for many locations during the year.
4. Solstices- the Northern Hemisphere is leaning 23.5 degrees toward or away from the sun.
o Summer Solstice-June 21 or 22 each year the axis is such that the Northern
Hemisphere is leaning 23.5 degrees toward the sun. The first official day of summer.
o Winter Solstices-December 21 or 22, the first day of winter. The Earth has moved to
opposite side of its orbit, Northern Hemisphere leans 23.5 degrees away from the sun.
On days between these extremes Earth’s axis is leaning at amounts less than 23.5
degrees to the rays of the sun.
5. Equinoxes-occur midway between the solstices. The vertical rays of the sun strike the
equator (O degrees latitude ) because earth is in its orbit so that the axis is tilted neither
toward nor away from the sun
o Autumnal (fall) Equinox-Sept 22 or 23
o Spring (vernal)Equinox-March 21or 22
6. Length of Daylight determined by Earth’s position in orbit.
o All latitudes receive 12 hours of daylight during the vernal and autumnal equinoxes.
o
Equinox literally means "equal night". On the vernal (spring) and autumnal (fall)
equinoxes, day and night are nearly the same length (the date on which day and night are
actually closest to the same length is called the equilux, and occurs a few days towards
the winter "side" of each equinox). Neither hemisphere gets more sunlight than the other,
so both have similar seasons (fall in one hemisphere and spring in the other).