GEOG 2130 Exam 1

Weather definition

Short term, day-to-day

Climate definition

Long-term, average

Atmosphere

A thin gaseous layer surrounding earth

Hydrosphere

All of earth’s water (including frozen portion known as cryosphere)

Lithosphere

Earth’s crust and portion of upper mantle; the entire solid planet

Biosphere

All the living organisms on Earth

Latitude

The angular distance north or south of the equator measured from the center of the earth. Positive values refer to degrees north, negative values refer to degrees south.

Parrallel

A line connecting all points along the same latitudinal angle

Longitude

The angular distance east or west of the prime meridian measured from the center of the Earth. Positive values refer to degreed east, negative values refer to degreed west

Meridian

A line connecting all points along the same longitude

Meteorology def

Very data-intensive disciplne, understanding how the data is stored and used is pivotal.

What do forecaster need to know?

Where their data comes from and how it is collected

NWS definition

National weather service

Where does weather data come from?

Radar, satellite, surface observations, upper air surroundings, airplane reports, people.

Is federally collected weather data free?

Yes, it is available to the public free of charge

NWS organization

Department of commerce (DOC), National Oceanic and Atmospheric Administration (NOAA), National Weather Service (NWS)

How many NWS forecasting offices in the US?

122

Who does international meteorological data?

World Meteorological Organization (WMO)

Surface observations

ASOS/AWOS stations

Upper Air observations

Radiosondes and Dropsondes

Remotely sensed observations

Radar and Satellite

Thermometer

Gather air temp not ground temp, usually over a natural surface, temp must be measured in shade

Wind collection

ASOS measure wind at 10m with anemometer and wind vane.

How is wind named?

Named by direction wind is coming from

Precipitation tipping bucket

Measures occurrence, amount and intensity of precipitation, number of tips recored electronically.

Visibility

Opacity of the atmosphere in a particular direction. Weather and obstructions can impact visibility

Cloud height

Base of the cloud layer

Ceiling

Lowest elevation where cloud bases cover at least have of the sky

Why is upper-air data necessary?

It provides data from a 3D view of the atmosphere

Aircraft Observations

Aircraft Communications Addressing and Reporting System (ACARS). Designates automated weather reports from commercial aircraft (temp, wind and sometimes dewpoint).

Radar

Radar detection and ranging.

How does Radar work?

Locates an object by means of high-frequency radio waves reflected by the object and analyzes the distance and direction of the waves bouncing off the object.

NEXRAD Radar

Next generation Radar. Replaced the WSR-57

What is doppler effect?

Radio waves squeezed of stretched based on precipitation movement.

What does NEXRAD radar enable measurements of?

Storm intensity and movement, wind fields within storms, detection of hail, rainfall estimates, tornadoes, upper level winds.

Radar Reflectivity

Amount of scattered energy proportional to size and concentration of particles. The echo displayed is called “radar reflectivity” will also detect dust, pollution and insects.

Radar Velocity

Usually displayed in color. Green = Toward radar, Red = Away from radar.

What is tight juxtaposition of inbound and outbound velocities called?

Velocity Couplet and it can indicate the presence of a tornado.

Dual polarization radar

Dual-polarization radars transmit both horizontal and vertical pulses. Comparing the behavior between the wavelengths can tell us about the type of hydrometer being detected.

What are ranging effects?

As the radar beam travels further away from the sampling sight there can be increased altitude which means it overshoots important parts of a storm. And there can be increased beam area where there is more avergaing and less detail.

Satellite data types

Geostationary and Polar Orbiters

Geostationary (GOES)

Orbits over equator in the same place.

Polar Orbiters (POES)

Orbits from pole to pole.

Visible Imagery

Very useful in daylight, brightness controlled by albedo. it has scattered and/or reflected sunlight it tracks storms and frnts.

Downside of Visible Imagery

Only useful in daylight, snow or sand can look like clouds.

Infrared Imagery

Measures heat, cooler object are brighter (white), cooler clouds are usually higher, useful at day and night.

Water vapor imagery

Wavelengths of 6.5-6.9 μm (absorbed by water vapor), Detects water vapor at 600- 300 mb. Middle and upper troposphere. Dark areas = dry air, Milky white = moist air, Bright white = clouds

Advantages/Disadvantages of Water Vapor

shows features in moisture in mid-upper troposphere only, Shows flow even where there are no clouds

Advantages/Disadvantages Of Infrared Imagery

“clouds” trackable even when area not in daylight, good for looping. Low clouds harder to see than upper; that can be used to gauge cloud height

Advantages/Disadvantages of Visible Imagery

Clouds confused with snow sfc: mountain snows are dendritic, clouds are not. More detailed than the other imagery. Shows low clouds equally well as high clouds. Poor for looping

Interpreting Visible Imagery

Satellite Measures: reflected solar radiation

Brightest Region: thick clouds, snow

Darkest Region: oceans, forests

Interpreting Infrared Imagery

Satellite Measures: emitted infrared (temperature)

Brightest Region: coldest clouds or surfaces

Darkest Region: warmest clouds of surfaces

Interpreting Water Vapor Imagery

Satellite Measures: infrared radiation emitted by water vapor only

Brightest Region: moist air

Darkest Region: dry air

Radiosonde

Sensors ascend through atmosphere tethered to helium-filled balloon

Dropsonde

Sensors dropped from aircraft (hurricane hunters)

Radiosonde data

Direct upper air measurements. Measures pressure, temperature and relative humidity.

What is main instrument used from vertical atmospheric profiling?

Weather balloon (radiosonde)

What are the mandatory levels for upper air observations?

1000, 850, 700, 500, 400, 300, 200, 150, 100 and 50 hPa. PLUS 925, 250, 70, 30, 20 and 10 hPa

How often are upper-air observation sounding taken?

Twice daily at 0z and 12z at 92 stations.

What does TTAA mean?

Mandatory Level Data; thermodynamic and wind dtat at madatory levels up to 100mb

What does TTBB mean?

Significant Level Data; thermodynamic data at significant levels up to 100mb

What does PPBB mean?

Significant Level Wind Data: wind data at significant levels up to 10mb, detailed wind profile

What do upper air station plots show regarding dew point?

Dew point depression, not actual dew point. If DD ≤ 5°C, fill in station circle

What doe upper air station plots use instead of pressure?

Height is used instead of pressure.

What does pressure do with height on atmosphere?

Pressure decrease with height in the atmosphere.

What does a 850mb map show?

Shows where warm and cold near-surface air is located. Good first guess at the precipitation type and shows advection of air masses.

What does 700mb map show?

Shows shortwaves: small subtle ripples of energy indicated by kinks in height contours. Saturation used as an indication of clouds/precipitation.

What is 500mb known as?

The “Steering Level” weather systems generally follow the flow at this level. Approximate halfway point between surface and tropopause.

What do 300/250mb maps show?

Ridges and troughs are visible in the upper atmospheric flow and it is the level of the jetstream.

Explain the Troposphere

Extends from surface to 11-17 km. Characterized by a decrease in temp with height.

Explain stratoshpere

Extends from 12-50km. Temperature increases with height.

Explain Mesosphere

Spans 50-80km. Temperature decreases with height.

Explain the Thermosphere

80km and up. Temperature increases with height.

Where does weather occur in the atmosphere?

Weather occurs in the troposphere.

What is the transition between troposphere and the stratosphere?

the Tropopause

What is the planetary boundary layer (PBL)?

The layer nearest to the surface of the Earth where friction influences atmospheric motion.

What is the free atmosphere?

The layer in which friction is no longer influential.

Explain the PBL

Generally lowest 1km of troposphere. Thicker when instability is high or underlying terrain is rugged. Very important for meteorologists

Explain the free atmosphere

Remainder of the troposphere lying above the PBL. Wind in this layer is mostly in a state of geostrophic balance.

What is air pressure?

The force exerted from the ongoing collision of gas molecules on all surfaces they come in contact with. (Ex. Air pressure in bike or car tires)

What is atmospheric pressure?

The pressure exerted by the eight of the air in Earth’s atmosphere. Result of gravity on Earth.

What is the average sea level pressure?

1013.25mb or 29.92in Hg

What is the density of the upper atmosphere?

Lower density of molecules meaning fewer collisions and lower pressure.

Density near Earth’s surface

Gravity compresses the air and makes it denser leading to more collision and higher pressure.

What happens to air pressure with increasing altitude?

Air pressure decreases with increasing altitude.

Where is over half the total mass of the atmosphere?

Lies below 5.5km because it is compressed by gravity.

What is Boyle’s Law?

If have constant temp, and increase the pressure, the volume will decrease (balloon being squished)

What is Charles Law?

If constant pressure, increase temp, volume will increase (hot air balloon; measure air Pressure when tires cool)

What is Dalton’s Law?

Pressure of some mixed gas is the sum of partial pressures of the components of gasses.

Ideal Gas Law is also known as

Equation of State

Why do we adjust pressure reading to sea level?

To compare pressures from different altitudes/elevations. Approximate correction: add 10mb for each 100m above sea level.

What kind of system is Earth’s weather?

An open system with many inputs.

Why study forces?

Describing the relationship between the inputs (forces) and the resulting weather is sometimes most effectively done with an equation Equations can clearly show us what will happen when one of the inputs is altered

What is acceleration proportional to?

It is directly proportional to the force acting on it and inversely to the mass being accelerated. Big force = Big acceleration. Big mass= Small acceleration.

Scalar definition

Something that has magnitude but no direction

What is a vector?

Something that has both magnitude and direction

Are force scalars or vectors?

Forces are vectors.

What are fundamental weather related forces?

Gravitational force, Pressure Gradient force and Friction.

What are apparent weather related forces?

Gravity, Centrifugal force, Coriolis force.

What is a fundamental force?

It exist regardless if where you are located.