Chapter 10 Flashcards
What are the four main atmospheric scales of motion?
Microscale (meters, seconds-minutes, e.g., dust devils), Mesoscale (1-100 km, minutes-hours, e.g., thunderstorms), Synoptic Scale (100-3,000 km, days-week, e.g., hurricanes), Planetary Scale (>3,000 km, weeks+, e.g., trade winds).
What are the two types of low-level turbulence?
Mechanical turbulence (caused by obstructions like buildings, trees) and Thermal turbulence (caused by surface heating).
When is thermal turbulence strongest and weakest?
Strongest in midday due to strong solar heating (>800 W/m²). Weakest at night when the surface cools.
How is wind direction measured?
Reported as the direction the wind is coming from, using a 360° compass (e.g., North = 360°, East = 90°).
What are the units for wind speed?
Knots (kt), miles per hour (mph), kilometers per hour (km/h), and meters per second (m/s). 1 kt = 1.15 mph = 1.85 km/h.
What is the highest recorded wind speed in the world?
253 mph (220 kt, 408 km/h) at Barrow Island, Australia during Cyclone Olivia, April 10, 1996.
What causes a sea breeze?
Land heats up faster than water, creating a pressure gradient where cooler air from the ocean moves inland.
When does a land breeze occur?
At night when the land cools faster than water, causing air to move offshore from land to sea.
How much can temperatures drop due to a sea breeze?
Sea breezes can reduce inland temperatures by about 5°C (9°F).
What happens during the summer and winter monsoons?
Summer: Land heats up, drawing in moist air from the ocean, bringing heavy rainfall (15-40 days of rain per month). Winter: Land cools, creating offshore winds that bring dry conditions.
Which place experiences the highest monsoon rainfall?
Cherrapunji, India, with ~425 inches (~10,800 mm) of rain per year.
When and why does a valley breeze occur?
During the day when the sun heats mountain slopes, causing warm air to rise.
When and why does a mountain breeze occur?
At night when the slopes cool, creating high pressure that forces cold air downslope.
What are Chinook winds and how do they affect temperature?
Warm, dry winds descending the Rockies’ eastern slopes, increasing temperatures by up to 20°C (36°F) in 1 hour.
Why are Santa Ana winds dangerous?
They bring hot, dry air to California, increasing wildfire risks, sometimes exceeding 90 kt (167 km/h, 104 mph).
What are dust devils and how do they form?
Small whirlwinds (a few meters wide, up to 100m tall) that form on clear, hot days over dry surfaces due to instability.
