How do you measure Wind direction? - answer✔wind vane/weather vane
How to measure Wind Speed? - answer✔Anemometer
Types of Anemometers; DEFLECTION ANEMOMETER - answer✔- 1st one
- 1450 Leon Battista in Italy
- Horizontal plate pushed by wind and connected to a spring
- compression of the spring proportional to wind speed
** Not good for light winds
Types of Anemometers; PRESSURE ANEMOMETER - answer✔- James lind 1774
- tube anemometer
- U tube - wind blows into a tube & pushes liquid in the tube
- (Dines anemometer 1892)
Types of Anemometers; CUP ANEMOMETER - answer✔- Thomas R. Robinson 1846
- 4 cups
- cup speed is 1/3 of the wind speed
- 3 Cup Anemometer - Canadian John Patterson
- more consistent behavior <3% error up to 100 km/h
Types of Anemometers; WINDMILL ANEMOMETER - answer✔- uses propeller to measure wind
speed
- aerovane used to ensure anemometer is pointing into the wind
Types of Anemometers; THERMOELECTRIC ANEMOMETER - answer✔- heated wire to above the
ambient temp
- rate of cooling of wire is proportional to wind speed
- in ancient times hair was used
Types of Anemometers; LASER RADAR ANEMOMETER - answer✔- same principle as Doppler
Radar (Shift in frequency i.e. train whistle at railway crossings, sirens on emergency vehicles)
- laser beams are back-scattered by moving air molecules
- Doppler shifted frequency of the back-scatter indicates wind speed
Types of Anemometers; SONIC ANEMOMETER - answer✔- Dr. Andreas Pflitsch 1994 (geologist)
- Measures how sound waves are modified by the wind
- deduces wind speed
Upper Level Winds: Radiosonde Drift (Weather Balloon) - answer✔Radiosonde: an instrument
carried by balloon or other means to various levels of the atmosphere and transmitting
measurements by radio.
- measures temp, pressure, humidity, wind
- usually pop around 30 km (halfway through Stratosphere)
- 34 in Canada, 1500 world wide
Dropsonde: Instruments dropped from Airplane
- designed to be dropped from an aircraft at altitude to more accurately measure (and
therefore track) tropical storm conditions as the device falls to the surface
Upper Wing Calculations - Geostrophic Winds - answer✔- Balance between PGF and Coriolis:
- Geostrophic winds are when pressure gradient force pulls from high pressure to low pressure
- coriolis force pulls moving objects to the right in NH and left in SH
- strength of Coriolis force is proportional to the speed of the object
- friction is negligible in upper level winds
2|Page
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Brightstars. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $10.49. You're not tied to anything after your purchase.
