Local winds
Local winds are winds caused by local temperature differences and terrain effects, rather than large-scale pressure systems.
They’re very important for low-level flying, takeoff, and landing.
Sea breezes
Sea Breeze (Day)
Land heats faster than water
Air rises over land → lower pressure
Cooler air flows from sea to land
✈️ Typically:
Starts late morning
Strongest mid–afternoon
Land breezes
Land Breeze (Night)
Land cools faster than water
Air rises over warmer sea
Wind flows from land to sea
Katabatic winds (kats come out at night)
A cold, dense air flow moving downhill.
🌙 When it occurs
At night
Ground cools rapidly → air becomes cold & heavy
⛰️ How it behaves
Flows down slopes and valleys
Can become strong and gusty
Accelerates due to gravity
Anabatic winds
A warm air flow moving uphill.
🌞 When it occurs
During the day
Sun heats slopes → air rises
⛰️ How it behaves
Flows up slopes
Usually gentler than katabatic winds
How to think about katabatic and anabatic easier
🧠 Memory Trick
Katabatic = Koming down
Anabatic = Ascending up
📌 Key takeaway
Katabatic = cold air sinking at night
Anabatic = warm air rising during the day
Diuernal variation what is it?
Diurnal variation means the daily cycle (over 24 hours) of temperature and wind caused by the Earth’s rotation and solar heating.
Temp variation in the day
Daytime
Sun heats the ground
Ground heats the air → temperature rises
Maximum temperature usually occurs:
👉 mid–afternoon (around 2–3 PM)
Temp variation night
🌙 Night
Ground loses heat (radiation cooling)
Air cools → temperature falls
Minimum temperature occurs:
👉 just after sunrise
Wind variation in the day
Wind Variation
☀️ Daytime (unstable air)
Surface heating → rising air → mixing
Stronger winds from aloft mix down
👉 Results:
Stronger surface winds
More gusts and turbulence
Low level jet streams
near ground level the surface friction is more causing lower wind speeds at night due to more air mixing. Although as the warmer air above has less friction this causes an increase in wind velocity. causing an increase in vertical windshear.
