# Presentation: 211657

## Fundamentalsof Weather

**Fundamentalsof Weather**

- Jon Nese and Jen Carfagno
- The Weather Channel
- February 22, 2004

**(Some)**

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## Meteorology 101

-   Weather and Air Quality:         The Issues

- _Outline_

-  Basic Weather Concepts

-  The “Models”

-   Weather Observations

-  Your Questions

## Meteorology 101

- Weather & Air Quality:
- Keys**:  Air motion**, **clouds**, and **precipitation**.

-  Wind, mixing disperse Pollutants!!

-  Clouds reduce sunlight and slow production of some pollutants.

- Horizontal:		Wind
- Vertical:		Vertical Motions, mixing

-  Precipitation cleanses the atmosphere.

## Meteorology 101

** ****Questions to Answer**

- What controls vertical motions?

- When and where do clouds and precipitation form?

- How, why, when, where does the wind blow?

## Mid-Latitudes

- Subtropics

- Tropics

- Polar Regions

- Meteorology 101

**Geographical Terminology...**

## Meteorology 101

**Layering of the Atmosphere**

## Meteorology 101

**Some Fundamentals**

-   Earth is heated unevenly: Tropics are warmer than the Polar Regions.

-   Nature tries to try to even out temperature differences.

-   Uneven heating sets atmosphere in motion and is the fundamental cause of all weather.

## Air Pressure

- Meteorology 101

**Air Pressure**

- On average, air weighs about 14.7 lb/in2

- 14.7 lb/in2 =29.92 “inches of mercury”

- Air Pressure varies over the globe

## Meteorology 101

**Changing Pressure - Winds**

- Take more out than put in – decrease pressure

*L*

*H*

- Put more in than take out – increase pressure

## Meteorology 101

**Changing Pressure - Temperature**

## Meteorology 101

**Pressure Differences Create Wind**

- Air moves from higher toward lower pressure

## Meteorology 101

- Air “converges” at lows, and rises.

- Air “diverges” at highs, and sinks.

## Meteorology 101

- Actual winds around highs and lows

**Reality is more complicated**

## Meteorology 101

-  Lows tend to bring cloudy, wet weather

-  Highs tend to bring fair, dry weather.

-  Rising air cools; water vapor in the air condenses to form clouds/precipitation

-  Sinking air warms and dries out.

## Meteorology 101

- Low or lowering pressure = “_L_ousy” weather

## General Circulation 

**General Circulation **

## Meteorology 101

-  Temperature differences concentrated

-  Zone of lower pressure where lows (storms) often form

## Meteorology 101

**Cold Front**
**Cold air advances**

**Warm Front**
**Warm air advances***

**Stationary Front**

## Meteorology 101

**What happens when air masses meet at fronts?**

- Cold air lifts the warmer air.
- Clouds and precipitation form.

## Meteorology 101

**Westerlies** - High-Altitude winds blow generally west-to-east 3-6 miles above mid-latitudes.

**Jet Stream** – River of fastest-moving air within the westerlies.

**Upper-Level Features**

## Meteorology 101

- Reality is messier ...

- Still, highs and Lows move with the westerlies and the jet stream.

## Meteorology 101

- Highs and Lows form and dissipate in synch with ridges and troughs in the westerlies.

**SINKING AIR**

**RISING AIR**

## Meteorology 101

- Stationary Front separates air masses

- LOW
- This is your life!

## Meteorology 101

- Area of low pressure develops along front

- H

- H

- L

**COLD**

**WARM**

- LOW
- This is your life!

## Meteorology 101

- Circulation around low sends cold air and warm air advancing

- H

- H

- L

- LOW
- This is your life!

## Meteorology 101

- Low and fronts move with the upper-air westerlies while circulating low-level air

- L

**COLD**

**COLD**

**WARM**

- LOW
- This is your life!

## Meteorology 101

- Typical cloud and precipitation shield of a low-pressure system and fronts

**Warm Sector**

- LOW
- This is your life!

- L

## Meteorology 101

- Intense lows often take on a “comma-cloud” shape when viewed from space.

## Meteorology 101

**Local Winds**

- Uneven heating working on a smaller scale

- L

**Sea Breeze**

**Heats faster**

## Meteorology 101

- Another control on vertical motions

- Vertical temperature structure of the atmosphere

**Inhibits Overturning**

**More likely to overturn**

- STABLE

## Meteorology 101

-  Typically, temperature decreases with altitude, so the lighter stuff (warmer air) is below the heavier stuff (colder air).

- In the Atmosphere...

-  Typically supports some overturning, especially in the boundary layer.

## Meteorology 101

- “STABLE”

**Inversion – **A layer of the atmosphere in which temperature increases with height.

- But Sometimes ...

## Meteorology 101

**Inversions inhibit vertical mixing. **
- Can trap pollutants in the lower atmosphere.

- Air sinks and warms near high pressure.

- Creates an inversion 1000s of feet above the ground.

## Meteorology 101

**Inversions inhibit vertical mixing.**** **
- Can trap pollutants in the lower atmosphere.

- Colder, heavier air trapped in valleys.

## Meteorology 101

-  Wind and rising air disperse pollutants.

**Key Ideas**

-  When air rises, clouds/precipitation can form.

-  Clouds reduce sunlight, which slows production of some pollutants; precipitation cleanses the air.

-  Air rises, and winds are strongest, in the vicinity of low pressure and fronts.

-  Air sinks, and winds tend to be light, in the vicinity of high pressure.

## Weather Forecasting

-   **Observations, observations, observations** (surface, upper-air, satellite, radar, etc)

-   **Knowledge** of how atmosphere works (e.g., high and low pressure, fronts, etc)

-   **Computer guidance** (the “models”)

-   **Personal experience** (“I’ve seen that before”)

- Meteorology 101

## Meteorology 101

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## Meteorology 101

** ****ASOS** – Owned and maintained by the NWS
-  Federal **AWOS** – Owned and maintained by the FAA
-  Non-Federal **AWOS** – Owned and maintained by state, city, and county agencies (incl. DOT), and private airports
-  Military bases – manually taken observations
-  CoOp observers – NWS volunteer network, manually taken observations
- *All are transmitted via FAA data lines to NWS to WSI to TWC.

_**ASOS**_** **– Automated Surface Observing System
_**AWOS**_** **– Automated Weather Observing Station

## Meteorology 101

-  Private Mesonets – such as AWS (Weatherbug), etc.,
-  Owned and operated by private network
-  Not available for use by other private companies

-  Public Mesonets – including RWIS, etc.
-  Owned and operated by government agencies
-  May not be centrally collected

-  Academic/Research Mesonets
-  Owned and operated by universities and research institutions
-  May be available for use by private companies

## Meteorology 101

## Meteorology 101

## Meteorology 101

## Meteorology 101

## Meteorology 101

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## Meteorology 101

- Weather forecasts have improved

## Meteorology 101

**Computer Models:  **
**Numerical Weather Prediction**

**Temp now**

**+**

**Change in Temp between now and future time**

- What processes change temperature?

-  Sunshine
-  Wind Direction
-  Evaporation
-  Pressure changes
-  Etc, etc, etc

## Meteorology 101

- ENIAC - University of Pennsylvania, 1945

## Meteorology 101

- Modern Computer Model Output (map form)

## Meteorology 101

- Modern Computer Model Output (map form)

## Meteorology 101

- FOUS62 KWNO 171200
- OUTPUT FROM ETA 12Z FEB 17 04
- TTPTTR1R2R3 VVVLI PSDDFF HHT1T3T5 TTPTTR1R2R3 VVVLI PSDDFF HHT1T3T5
- DCA//504026 02523 370707 34989496 ORF//766649 -1014 340515 40039999
- 06000527423 01319 331007 34019596 06007938417 02008 310314 41030000
- 12000736828 -0615 300709 34019696 12015968326 -1805 270120 41030000
- 18000885821 -0814 280212 32009696 18001968328 -6009 253518 39020000
- 24000925418 -1114 263614 30989795 24000966327 01213 233422 34019897
- 30000562608 -3115 243414 30039794 30000784707 -1612 233521 32029796
- 36000552244 -1619 233316 35019795 36000602016 -2418 223314 35049895
- 42000644246 -1316 192811 38000098 42000602335 00618 203113 40029999
- 48000485637 06212 152415 41010099 48000534040 -2716 182620 43020399

- Modern Computer Model Output (tabular form)

## Meteorology 101

- Some “folklores” are useful

## Fundamentalsof Weather

**Fundamentalsof Weather**

- Jon Nese and Jen Carfagno
- The Weather Channel
- February 22, 2004

**(Some)**

## TWC Mission

-  Communication of **uncertainty** - the atmosphere is a very complicated system (hurricanes, March 2001 snowstorm)
** ****Educate** the public

**TWC Mission**
- Making a difference in people’s lives, one forecast at a time.

- Meteorology 101

## Operations Overview

- Meteorology 101

## Meteorology 101