Download Weather

WEATHER
And
FORECASTING
WEATHER
AND
CLIMATE
•Weather is defined as the state of the
atmosphere at some place and time,
usually
expressed
in
terms
of
temperature, air pressure, humidity, wind
speed and direction, precipitation, and
cloudiness.
Meteorologists study weather.
•Climate is defined in terms of the
average of weather elements (such as
temperature and precipitation) over a
specified period of time (30 years
according to the World Meteorological
Organization).
It is normal for the weather to change on a daily or even hourly basis. But when
the average pattern over many years changes, it is a sign of climate change.
Image source: http://www.weather.com.
WEATHER
AND
CLIMATE

The Climate and Weather of a region can
be
determined
through
certain
measurable properties such as: a.)
atmospheric temperature, b.) humidity,
c.) type and amount of precipitation, d.)
cloudiness, e.) wind speed and direction,
and f.) air pressure
•At high temperatures molecules expand,
become less dense and thus go up; while at
low temperatures, molecules contract,
become more dense and sink.
•Because warm air is less dense, it advances
upward and the cooler and denser air mass
stays below it.
•As the warm air rises, the moisture
condenses and forms thin clouds, then
continues to form other kinds of cloud at
different altitudes.
•Slowly, the clouds will thicken and the area
below it will have dark, cloudy days or
showers.
•As the clouds further thicken, it will become
heavier, sink to a lower altitude and
eventually fall down as well.
•A warm front usually produces light to moderate precipitation
over an area, because it advances very slowly. On the other
hand, a cold front advances more rapidly and forcefully than a
warm front. These forceful movement causes violent weathers
such as thunderstorms.
•Because cold air mass is
denser than warm air
mass, it advances at a
low altitude, meaning, it
keeps close to the
ground while it moves.


We have extremely bad or violent weather
such as, tornadoes, which form over land, and
cyclones, which form over oceans and travel
over land.
Most cyclones originate from the large
oceans where an abundant supply of moist air
comes from.


Centers of low pressure that travel from west
to east across the Earth and which last for
few days or a week.
Those cyclones that come from the Atlantic
ocean are called HURRICANES, and from the
Pacific oceans called TYPHOONS, and those
from the Western Pacific are called STORMS.





Thunderstorms occur when a large mass of cold air slides under a
large mass of warm air. Heavy rains come down very quickly. Flashes
of lightning are also often seen during a thunderstorm. Lightning is
basically an electrical charge released into the atmosphere.
A tornado is a funnel of strong winds that spiral upward. They can
reach very high speeds and be very powerful.
Tornadoes can destroy trees, houses, and other large objects.
A hurricane is a very large and often violent tropical storm.
Hurricanes can be hundreds of kilometers wide and the winds of
one of these storms can be very fast. Hurricanes form over the
ocean and are made up of swirling winds. They usually produce a lot
of rain.
A blizzard is a heavy snowstorm with strong winds. Blizzards
produce heavy snowfalls.
WEATHER
AND
CLIMATE
Image Credit: NASA
2009-2010 Eastern US
“Snowmageddon”
2010 Northern Pakistan Floods
Image Credit: NOAA
2010-2011 Texas’s Worst Drought
and Fire Season in Recorded History
2012 Hurricane Sandy


Group A- HUMID TROPICAL- does not have
any winter season. Each month has an
average temperature of 18˚Celcius.
e.g.: Philippines, Malaysia, Indonesia
Group B- DRY CLIMATE- there is more
evaporation than precipitation; found on Arid
or Semi- arid regions.
e.g.: Egypt and countries in Middle East


Group C- HUMID MIDDLE LATITUDE
CLIMATES WITH MILD WINTERS- the average
temperature of the coolest month is of 18˚C but
above - 3˚C.
e.g.: Florida and CA
Group C- HUMID MIDDLE LATITUDE
CLIMATES WITH SEVERE WINTERS- average
temperature of the coolest month is below- 3˚C,
and an average temperature that exceeds 10˚C
during its warmest month.
e.g.: Chicago and Michigan

Group E- POLAR CLIMATE- occurs at the pole and
extremely cold. The average temperature during its
warmest month is below 10˚C. e.g.: Antarctic and
Arctic Regions.
WEATHER
AND
CLIMATE
•Meteorologists focus primarily on real-time
(current) data to predict local or regional
atmospheric conditions for the hours, days, or
weeks ahead. Thus, weather prediction tends to be
more local and relates to conditions in the
immediate future from days to weeks.
•Climate scientists, on the other hand, look at
atmospheric conditions in terms of averages and
trends (patterns) that have occurred over many
decades, centuries, and millennia.
WEATHER
AND
CLIMATE
Weather is variable, but can be averaged over time to indicate climate trends.
Therefore, climate scientists can use weather data plus proxy data to help
them identify previous trends to improve their predictions of future trends.
What Are Proxy Data?
Proxy data include biological, cryological (which refers to frozen water),
geological, and historical records that scientists use to deduce Earth’s
atmospheric conditions in the distant past. By examining evidence such as the
tree rings of old-growth trees and ice core samples taken from glaciers,
scientists can figure out what Earth’s temperature, greenhouse gas
composition, and precipitation levels were like over the course of its geologic
history.
WEATHER
AND
CLIMATE
Weather balloons, satellites, specially designed airplanes,
and radar and other ground-based data collection
instruments are used to
• measure wind speed,
• precipitation,
• air temperature,
• humidity levels, etc.
Reliable records have been kept since 1800s and provide
accurate weather forecasts (weekly and daily).
Sophisticated Earth-observing satellites equipped with
remote-sensing equipment circle the globe to
• record sea surface and other temperatures,
• measure atmospheric gases and rainfall amounts,
• take visible and infrared photos of Earth’s surface, and
• calculate Earth’s outgoing infrared and reflected solar
radiation.