Transcript Weather Station Models

Weather
What is Weather?????
Weather Animation
Weather Definition
• Weather – state or condition of
the variables of the atmosphere at
a given time
• Weather variables – temperature,
air pressure, wind, moisture, cloud
cover, precipitation, storms
• Weather occurs in the
troposphere (lower layer of the
____________
atmosphere)
Heat energy
***________________is
what
Temperature
• Three Scales: Fahrenheit, Celsius, Kelvin
• Isotherms – lines that connect
equal lines of temperature
Where can we find this table??
Sample Conversion
Questions
What instrument is used to measure
temperature?
A thermometer
____________________________
_____
Question 1. The highest air
temperature ever recorded in
Albany, NY was 104° F. This
temperature is equal to??
40°C / 313°K
Heating the Atmosphere
• The __________is
sun
the original source of almost
all the heat in the atmosphere
• The more the insolation at a location, the
Earth’s surface and the
warmer ___________________
atmosphere will be
__________________
Average Temperatures Animation
The ways in which the atmosphere is
heated include:
Conduction: moves heat from
Earth into the atmosphere
______________________as
air touches
Earth’s surface
Absorption:
1. Absorption of insolation from the sun by
__________________moves
heat into
gases and aerosols
atmosphere
2. Absorption of ________________
infrared radiation
________________________moves
heat
given off by Earth’s surface
into atmosphere
Example of conduction
warming the air
Example of absorption
warming the air
The ways in which the atmosphere
is heated include:
Condensation: The release of large
stored heat
amounts of _____________,
which will
directly heat the atmosphere
This happens when __________________
clouds, fog, dew, and
___________________
frost form
Coriolis Effect: Due to rotation and winds,
causes friction
___________________________
between air and Earth’s
_______________
surface
How condensation warms
the air
Another Important Heat
Transfer
Convection – Heat is transferred
within the atmosphere due to
differences
in air density
_____________
___________________
difference in air pressure
The difference in density causes a
Displacement of air/water
___________________________
The difference in air pressure
causes the air to move in circular
patterns, which are known as
convection currents
__________________
Transfer of heat in atmosphere
through convection
Expansion and compression
expands
When a gas __________,
its
temperature _______________
decreases
(Air rises expands and cools)
compresses its
When a gas ____________,
increases
temperature ____________
(Air sinks compresses and warms)
Therefore, air temperature
decreases with increasing altitude
because the air rises, expands, and cools
_______________________
Weather
Instruments
Thermometer
Measures temperature
Anemometer
Measures wind speed
Wind Vane
Measures wind direction
Barometer
Measures air pressure
Rain Gauge
Measures rain amount
Psychrometer
Measures moisture in the air
Weather Station
Models
Weather Models
Weather Station Models:
used to describe weather
conditions:
Using your reference table:
Find Temperature, Dewpoint,
Pressure, Pressure Trend,
Wind Direction, Wind Speed,
Visibility of the model below
38
10
28
100
Weather Models 2
Do Now:
• Air rises ___________
expands
and ____________
cools
• Air sinks compresses
___________ and warms
____________
Draw this picture and show what happens to air and show
where clouds would form:
Atmospheric Moisture
• Exists in ____________________in
solid, liquid, and gas
atmosphere
• Water enters the atmosphere by:
– Evaporation – liquid changes into gas
– Transpiration – plants release water vapor
– Evapotranspiration – evaporation
and transpiration together
• Remember it’s
sun
the _______
that provides
the energy for these to occur !!!
The net evaporation rate
of water is determined
by:
1. Amount of energy:
More energy(higher temp)=Faster evaporation
2. Surface area of the water
More spread out = Faster evaporation
3. Degree of saturation
More saturated = Slower evaporation
4. Wind speed
Greater wind speed = Greater evaporation
Humidity
vapor in each unit
• Absolute Humidity water
volume of air (or moisture capacity)
more
- hotter air can hold __________water
vapor
than cold air
• Relative humidity –ratio of the amount of water
vapor in the air to maximum amount it can
hold
– The one you see in forecasts
Which is heavier?
• Which is heavier dry air or wet air?
O
N2 2
N2
O2
vs.
N2
H2O
H2O
O2
H₂0 turns out to be a lighter
molecule than most of the
molecules in the air (0₂ and N₂
vs. H₂0)
For a given volume of space DRY AIR IS HEAVIER THAN MOIST AIR
because--molecular weight of H2O is 18
molecular weight of nitrogen is 28
DRY AIR IS MOSTLY COMPOSED OF NITROGEN
Would a baseball travel further when it
is warm or cold?
When air WARMS, it expands. This warming and expansion lowers the
density of the air. This produces longer flight distances, all else being
basically equal.
Would a baseball travel further on a
night where the air is saturated or dry?
At a HIGHER HUMIDITY, baseballs will travel a little further, all else being
equal. At the same temperature, air with a higher dew point will be less dense.
Dew Point
• Dew point – temperature at which air can no
longer hold all of its water vapor, and some of
the vapor condenses into liquid water
**If air temp drops below dew point Water vapor in the air will condense
into liquid water**
Dew Point
Example:
• Today we read that the dew point of the
air is 44°F; the present temperature is
75°F. This means that if the temperature
were to fall to 44°F tonight, water in the air
would condense (forming dew). If the
temperature were to only fall to say
50°F, no dew would form!
Measuring Moisture
• Sling Psychrometer instrument
–
used to measur
relative humidity and dew point
Contains:
dry-bulb thermometer ordinary thermometer
1. __________________–
wet-bulb thermometer thermometer with wet
2.__________________–
wick around it
To convert relative
humidity and dew point
You must use page 12 of ref. table
1. Subtract: dry bulb temp – wet bulb
2. Locate dry bulb on left side
3. Locate answer to step 1 on top of
chart
4. See where those two numbers
meet
****Make sure you are using the
correct chart: dew point or
relative humidity
Try a couple examples:
1. What is the relative humidity where the dry
bulb temperature is equal to 18oC and a wet
bulb temperature of 15oC?
Step 1: 18oC - 15oC = 3oC
Step 2: Dry bulb temp = 18oC
Step 3: Locate number from
step 1 on top of chart
Step 4: Find where two
Numbers meet
Try a couple examples:
2. What is the dew point temperature when
dry bulb temperature is equal to -4oC and a
wet bulb temperature of -5oC?
Which weather station model shows
the highest relative humidity? Why?
86
57
77
50
1
2
72
77
67
75
3
4
Which weather station model shows
the highest relative humidity? Why?
86 converts
to 30
57 converts
to 14
77 converts
to 25
50 converts
to 10
1
72 converts
to 22
67 converts
to 19
2
77 converts
to 25
3
75 converts
to 24
4
Which weather station model shows
the highest relative humidity? Why?
86 converts
to 30
57 converts
to 14
77 converts
to 25
Difference
of 5
50 converts
to 10
1
72 converts
to 22
Difference
of 4
77 converts
to 25
67 converts
to 19
75 converts
to 24
Difference
of 3
3
Difference
of 1
2
4
Which weather station model shows
the highest relative humidity? Why?
Relative
Humidity =
66%
Relative
Humidity =
60%
1
2
Relative
Humidity =
92%
Relative
Humidity =
75%
3
4
Cloud Formation
1. Air
rises and cools
_________________________
2. Air reaches
its dew point
____________________
3. Water begins to
condense
______________,
meaning it
gas to a
will change from a _______
liquid
____________
4. Water droplets form on
condensation nuclei
_______________________
(dust particles / aerosols)
Precipitation
• Precipitation –
___________________________
___________________________
The falling of liquid or solid water
_____________
from clouds towards Earth’s surface
• In order for precipitation to occur
the ice crystals or water droplets
___________________________
must be big enough
___________________________
_ so that
they will fall under the influence of
gravity
• Precipitation occurs when liquid or sold
water could particles collide becoming
heavy enough to fall
____________________
• Forms of precipitation include:
__________________________________
rain, drizzle, snow, sleet, freezing
_________________________
rain and hail
Precipitation
SNOW:______________________________
Falling ice crystals, below 32°F
SLEET: _______________________________
Rain freezing as it falls, above 32°F
FREEZING
Rain freezing on contact with Earth’s
RAIN:_________________________________
_____________________
surface, above 32°F
RAIN:_________________________________
Falling liquid droplets, above 32°F
• Precipitation will often
remove pollutants that have been
___________________________
emitted into the atmosphere
___________________________
__
Video:
http://www.youtube.com/watch?feature=endscreen
&NR=1&v=nCyhwcs2wog
To convert pressure on a
station model
•
You must use page 13 of ESRT
•
If the barometric pressure on a station
model reads 196; it is <500 so we add 10
in front and a decimal place BECOMES
1019.6 mb
•
If the barometric pressure on a station
model reads 696; it is >500 so we add 9 in
front and a decimal place BECOMES 969.6
mb