Skip to main content

Weather Fundamentals

Composition of the Atmosphere​

Layers:

Thermopause Thermosphere Mesophere Stratosphere Ozone layer Troposphere

Weather happens in the Troposphere

Atmosphering Circulation​

Cause of all weather is uneven heating of the earth's surface

Coriolis Force​

Wind caused by earth's rotation

Atmospheric Pressure​

Sea level 14.7ls

Every 1000ft, pressure drops about an inch of mercury

Aneroid wafers

Winds and Currents​

The air over the sea heats up more slowly than over land.

High pressure - usually brings better weather Move clockwise outwards and downwards (COD) COD

Low pressure - brings worse weather counter clockwise, inwards, upwards??

Bom cyclones

To get a tailwind You want to be south of a low pressure, north of a high pressure

Effects of Obstructions on Winds​

Obstructions can cause downdrafts

Mountain Winds​

Cross mountains at a 45degree angle - makes it so you can turn around without having to turn as much (90 egrees instead of 180)

Winds above 20kts gets ...scary??

Windshear​

alt text

Spot #1 you get an increase in performance

If you had a headwind and then

Don't fly if there's any windshear.

Fly a landing approach faster in wind shear

Atmospheric Stability​

The atmosphere's ability to resist vertical lift

Adiabatic Heating and Cooling​

2 degrees / 5.4 F temperature drop per every 1000 ft of altitude

Moisture and Humidity​

Relative Humidity

RH represents the amount of water in air in percentage

Gives us insight into if cloud are going to form

Dew point

At 100% humidity, there will be some sort of visible moisture

Temerature Inversions​

When you go up in altitude and it gets warmer instead of cooler

Cloud Characteristics​

Stratus clouds: Low level, stable clouds Stratocumulous

Towering cululus or cumulonimbus are tall and have a lot of

Stratiform Clouds: The blanket clouds that stretch a ways

Cumulus clouds are fluffy

Air Masses​

Cold fronts​

Usually bring worse weather and move faster

All fronts bring wind changes and temperature changes

Warm Front​

Occluded Front​

When a cold from overtakes a warm front and everything mixes together

Thunderstorms​

Three stages

  • Cumulus
  • Mature
  • Dissipating
    • Most dangerous because of down drafts

3 ingredients

  • moisture
  • unstable air
  • lifting force

If there is a thunderstorm, you're supposed to stay 50-60 nm away. They can throw hail really, really far. (About 15m?)

Characterized by the anvil top shape

Water molecule is sent up. When it goes up, it becomes ice. The ice falls, hits the water molecules. When it hits, it creates static electricity.

Icing​

Three types

Clear icing: rain hits aircraft and then freezes Rime: Freezes right away. Causes the most drag and decreases lift Mixed

Want to land if you start to get icing

Fog​

Radiation Fog​

Think zombies on farm fog

Forms on clear nights with low temp and dew point spread is low/small

Overnight, air cools to it's dew point, condenses and creates fog

Advection Fog​

Cold air mass moving over a warm air mass, fog happens from the cooling "Marine layer"

Steam fog​

Air that moves over a warm body of water, heats up, forms steam. Less common

Upslope Fog​

Air mass is forced up a hill, cooled to it's dew point

Precipitation fog​

Extra fine, small rain particles

Freezing fog​

Less common around here.

Air particles frozen and suspended in the air

Need to know -

Microbursts Advection and radiation fogs Thunderstorms Vergo clouds - indication that there's a microburst

IMSAFE I Medication Stress Alchohol Fatigue E

Quiz​

1. Decode this METAR:
KHIO 131653Z 13005KT 6SM -RA BR OVC033 04/04 A2979 RMK AO2 SLP090 P0003 T00440039

Hillsboro
13th at 8:53am
Wind 130 @ 05kts
6SM visibility
Light rain
Mist
Overcast 3300
Temperature 4°C
Dewpoint 4°C
Altimeter 29.79


2. What is a PIREP? Are there different kinds? What are they for?

A pilot report
There can be urgent or normal PIREPs
They are often for cloud cover, icing, turbulence, wind shear, etc.


3. Decode this TAF:
KHIO 131137Z 1312/1412 14004KT 4SM BR OVC005
FM131800 14008KT 5SM -RA SCT010 OVC025
FM132100 13008KT 2SM -RA BR BKN007 OVC015
FM140500 15010KT 4SM -RA BR OVC015

Hillsboro
13th at 3:37am from the 13th at 12 to the 14th at 12
Winds 140 @ 04kts 4SM visibility mist overcast 500
From 13th at 10am winds 140 @ 08kts 5SM visibility light rain scattered 1000 overcast 2500
From 13th at 1pm winds 130 @ 08kts 2SM visibility light rain mist broken 700 overcast 1500
From 13th at 9pm winds 150 @ 10kts 4SM visibility light rain mist overcast 1500


4. What are the 3 kinds of AIRMETS?

Tango - Turbulence
Sierra - Mountain Obscuration or IFR
Zulu - Icing


5. What are examples of some SIGMETS? How long is a convective SIGMET valid for?

Tango, Sierra, Zulu, and a convective SIGMET is valid for 2 hours.
Tornadoes, thunderstorms are examples.


6. What is Hypoxia vs Hyperventilation?

Hypoxia is not enough oxygen in the body
Hyperventilation is too much CO2


7. How long should you wait after drinking to fly?

8 hours bottle to throttle, 0.04 blood alcohol


Details

8. What does IMSAFE stand for? Illness
Medication
Stress
Alcohol
Fatigue
Emotion


9. What are the 5 hazardous attitudes?

Macho: "I can do it!" Anti-Authority: "Don't tell me what to do!" Impulsivity: "Do something quickly!" Invulnerability: "It won't happen to me!" Resignation: "What's the use?"