1: Monitoring the Weather Flashcards
Weather vs Climate
Weather is the state of the atmosphere at a place at any given time
Climate is the long term average of weather conditions
What are the atmospheric variables of weather
CHPWPT
Cloud
Humidity
Precipitation
Wind
Pressure
Temperature
How is climate determined
Atmospheric variables: CHPWPT
and weather data that is averaged over 30 years or more
Is climate constant throughout the world?
No, the tropics have warm and humid climate
Poles have cold and dry climate
It is rare that the elements of the weather equal to the climatic normals
State of atmosphere (10)
Maximum Temperature
Minimum Temperature
Dewpoint or Relative humidity
Rainfall amount (in mm)
Snowfall amount (in cm)
Wind direction
Wind speed
Air pressure (weight of air column)
Sky cover (fraction of cloud cover)
Weather Watch or Weather Warning
When does the day’s minimum temperature occur?
sunrise
What is in Fernie, BC? and the type of data it collects
automated surface weather station. Collects data on
Rainfall
Humidity
pressure
Temperature
Radiation
Wind speed and direction
What is the global surface observation network
Monitors the land and ocean. Has blind spots like in high latitudes and desert regions
Where and how many surface observations in Canada and how often is it recorded
Most stationed at the US border:
Land: 10k stations
Ocean: 1k buoys and 7k commercial ships
Recorded at 0000, 0600, 1200, and 1800 UTC (every 6 hours)
Radiosonde and examples
Upper air observations. package of instruments that measure pressure, temperature, height, and moisture and send this information back to the surface through radio transmissions
Ex: weather balloon. Bursts at 25km altitude
Ex: sounding: vertical profile of the atmosphere that is generated
Vertical atmospheric profile
From sounding. Also called Skew T log P
one line is temperature and the other is dew point
- when temperature and dew point are closer together it is humid and when they are far apart it is dry
- wind barbs gives wind direction and speed
-gives mixing ratio
image 1
Weather radar
emits pulses of microwave energy which is then reflected by raindrops, snowflakes, or hailstone → shows structure and intensity of rainfall
can locate and track movement of precipitation and thunderstorms
produces composite radar image
limitations of weather radar
5-200km limitation due to curve of earth
cone of silence: can’t measure above
Satellite based observation, types, and example
satellites can see in other wavelengths not visible to us so can give info on stuff like water vapor in atmosphere
Ex: GOES satellite imagery → Geostationary Operational Environmental Satellite
Types:
1. geostationary satellite
2. polar orbiting satellite
Which direction does atmosphere move in midlatitudes and example
west to east
Ex: jet stream
geostationary satellite
-36k km above earth’s surface
-sub satellite point lies on equator
-samples good data in tropics and subtropics because of fixed position
-completes a cycle in 24 hours
image 2
polar orbiting satellite
-1k km above Earth’s surface
-samples overlapping north-south strips while Earth rotates eastwards
-sun-synchronous satellites sample each point on Earth twice daily
-combine geostationary and polar orbiting to get complete picture
image 3
Types of satellite imgaes
visible satellite
infrared satellite
water vapor (IR) satellite
Visible satellite
-Shows reflected sunlight so depends on surface and its albedo
-Only available during the day
-Brightness indicates amount of water → ex: cloud
-Cloud pattern can be estimate
infrared satellite image
-Depends on temperature of emitting object
-IR image depicts temperature of clouds or Earth’s surface and estimates cloud top heights
Energy emitted/transmitted per surface area is E = T^4
water vapor satellite
-means high water vapor
-shows transport of moist air
-indicates upper clouds
surface weather map
-atmospheric variables monitored by both surface and space based stations to make a weather map
-have special symbols to represent state of the atmosphere
image 4
temp behind cold and warm front on surface weather map
behind cold front: cold air mass
behind warm front: warm air mass
sky watching
watch the sky - traditional way of understanding the atmosphere using clouds
what are clouds
Clouds are composed of tiny water droplets, ice crystals, or both, and the nature clouds can provide very useful information about the potential of future precipitation.
weather front
transition zone between two air masses of different temperature
cyclone wind characteristics
surface low: winds spiral counterclockwise in the northern hemisphere and clockwise in the southern and inwards. Central pressure would be the lowest
image 6 (B)
whats a cyclone
-warm and cold fronts momentum rises surface temperature and pressure
image 5
anticyclone wind characterstics
Surface high: winds spiral clockwise in the northern hemisphere and counterclockwise in the southern and outwards. Central pressure would be the highest
image 6 (A)
isobars
blue lines in image 6. Shows pressure
Warm front
- dancing warm (light) air slides over cold (heavy) air
-Convection: warm air rises up
-Warm air overrides cold air and push gradually
image 7
Cold front
advancing cold (heavy) air pushes under warm (light air) and results in convection
-Results in snowsquall (short lived and heavy snowfalls)
image 7
How do clouds form
Cold air is more dense than warm air so when a warm air mass meets a cold air mass, the cold air ends up below the warm air. Once the air has risen, it cools and forms clouds
image 8
order of clouds from low to high altitude levels
nimbostratus, altostratus, cirrostratus, cirrus
image 8
Types of clouds
high thin/wispy cirrus clouds
low clouds
fair weather cumulus clouds
thunderstorm cloud
High thin/wispy cirrus clouds
-consists of ice needles
-arrival of cirrus in western sky often indicates approaching warm from
low clouds
-Consist of supercooled water droplets
-Vertical and horizontal size are similar
-Often caused by daytime surface heating
-Often vaporize at sunset
thunderstorm cloud
cumulus cloud builds vertically into a cumulus tower and merges with neighbouring towers to form a thunderstorm called cumulonimbus
differential movement of clouds
-Clouds move with wind
-Winds at different heights may blow with different speeds in directions. Depends on height of clouds
-Change often associated with temperature changes
Timekeeping
weather observations made simultaneously at 0000 and 1200 UTC
Examples of public bulletins (5)
weather watch
weather warning
special weather statement
severe weather warnings
weather radio
weather watch
to alert the public that conditions are favourable for the development of severe weather
weather warning
issued when severe weather is occurring and hazardous conditions are highly probable
special weather statement
advisory of weather that may be of some inconvenience or concern
severe weather warnings
-criteria differ from region to region
- tornado, hail, blizzard, heavy snowfall, wind, gusts, flash flooding
weather radio
broadcasts local forecasts 24 hours a day on special frequencies
- Depending on local topography, the maximum range of broadcasts of the NOAA weather
radio is about ____________ kilometers.
a. 10
b. 100
c. 20
d. 65
d
- Viewed from above in the Northern Hemisphere, surface winds blow ___________ about the
center of a low pressure system.
a. clockwise and outward
b. clockwise and inward
c. counterclockwise and outward
d. counterclockwise and inward
d
- Weather systems usually cross the United States in
a. one day.
b. several days.
c. twenty or so days.
d. one month.
b
- Air pressure can be thought of as
a. air temperature.
b. wind speed.
c. weight of the overlying air.
d. weight of the underlying air.
c
6 . Weather radar monitors the movement of
a. cloud particles.
b. precipitation.
c. planets
d. river flow
b
- Viewed from above in the Northern Hemisphere, surface winds in a high pressure system
blow
a. clockwise and inward.
b. clockwise and outward.
c. counterclockwise and inward.
d. counterclockwise and outward
b
- As a general rule, lows that track from west to east across southern Canada produce
___________ precipitation compared to lows that track along the Gulf of Mexico coast.
a. more
b. a thousand times more
c. less
d. about the same amount of
c
- Meteorologists use water vapor satellite imagery to
a. determine the humidity in the air next to Earth’s surface.
b. monitor the temperature of the tops of clouds.
c. track the movement of water vapor at higher altitudes of the atmosphere.
d. measure the surface wind speed in a hurricane.
c
A cloud in contact with the Earth’s surface is known as
a. a cumuliform cloud.
b. fog.
c. a cirrus cloud.
d. a thunderstorm.
b
Wispy-appearing clouds that occur at high altitudes are composed of mostly
a. tiny liquid water droplets.
b. tiny ice crystals.
c. methane.
d. solid carbon dioxide
b
How to read a wind bar from a vertical atmospheric profile
image 1
* One line is called the barb
* Wind is measured in knots (nautical miles per hour) → 1 m/s = 1.94 knots
* Where the wind is going to is the end that has no barbs
* wind named where it is coming from. Ex: wind going east is westerly wind
how does low pressure system work
Image 5
after you get warm air, cold air follows due to anticlockwise direction. The blurry blue is precipitation like snow, rain, etc…
