What is a climate
7.E.1.4 Weather Prediction C.Notes
defined by average temperature, precipitation, humidity, air pressure, and wind, over
time in a particular place
Climates on Earth
temperate (middle latitude)
 Summers can be hot but winters are not very cold
Polar
 Consistently cold temperatures
 Every month of the year averages below 10 degrees Celsius
tropical
 Close to equator = hot
 Receive most sunlight
 Can be dry or heavy rain
Dry (arid)
 Usually get less than 25cm of rain per year
 Include deserts
 Not all dry zones are hot (Gobi Desert is cold)
Continental
 Wider temperature range
 Much colder winters
What is a weather forecast
an attempt to make accurate predictions of future weather
 The accuracy of weather prediction is improving as technology advances
 Long range is more difficult than short-range weather predictions
What does a weather map
show
precipitation, wind direction, temperature, cloud cover, high or low pressure, cold and
warm fronts, stationary and occluded fronts
What direction do weather
systems generally move
Technology
Types of satellite maps
west to east in US
greatly influenced the ease and accuracy of making weather predictions
computer
 Weather data at thousands of locations can be gathered instantaneously and
applied to weather prediction to produce weather maps
Satellite weather maps
 Visible satellite map
o snapshot of the earth and is only available during the day as it uses light
from the sun to detect the clouds
o Low clouds are dark and high clouds are lighter
 Infrared satellite map
o allows you to see cloud cover whether it is day or night
o measure the temperature of cloud tops, which we can translate into cloud
cover
o Strong to severe thunderstorms will normally have very cold tops
 water vapor satellite map
o indicate how much moisture is present in the upper atmosphere
o useful for indicating where heavy rain is possible
What is radar




Weather data collection
Main cloud types
7.E.1.4 Weather Prediction C.Notes
electronic instrument, which determines the direction and distance of objects that
reflect radio energy back to the radar site
stands for Radio Detection and Ranging
what meteorologists use to see rain or snow
Doppler radar
o what meteorologists use to see rain or snow
o gives forecasters the capability of providing early detection of severe
thunderstorms that may bring strong damaging winds, large hail, heavy
rain, and possibly tornadoes
wind speed
wind direction
air temperature
 measure of the energy of molecules
 the more energy the molecules in air have, the hotter it feels
relative humidity
 compares the actual amount of water vapor in the air with the maximum
amount of water vapor the air can hold at that temperature (its capacity)
air pressure
cirrus


high level clouds and due to high altitude, the water is almost frozen to form ice
crystals
isolated Cirrus clouds  do not indicate any instability in the weather and may
not bring rain.
if the clouds are dense they often indicate that a storm might be approaching

stratus
 layered clouds that usually bring a drizzle and there is widespread rain and in
some cases ocean air
cumulus
 neutral weather clouds
All the other clouds are combinations or variations of these types
Cold front vs. warm front
Cold front
 leading edge of a cooler air mass of air, replacing at ground level a warmer mass
of air
 cooler, denser air wedges under the less-dense warmer air, lifting it
 upward motion causes lowered pressure along the cold front and can cause the
formation of a narrow line of showers and thunderstorms when enough
moisture is present
 weather map  cold front is marked with the symbol of a blue line of
triangles/spike pointing in the direction it is traveling
 can move up to twice as fast as warm front and can produce sharper changes in
the weather
 usually associated with an area of high pressure
warm front
 leading edge of a warm air mass that displaces colder air, bringing a
temperature increase and heavy rain where the front makes contact with the
7.E.1.4 Weather Prediction C.Notes

ground
weather map  represented by a red solid line with semicircles pointing
towards the colder air and in the direction of the movement