WIND

• wind = air moving from high to low pressure
• is invisible / seen by it's effect on other things
• moves around / over/ forced through obstacles
• at fast speeds wind currents similar to white water
• hence wind-tunnels, eddies, sudden surges etc
• go to Beaufort Wind Scale

TEMPERATURE

• Drops by 1-2°C per 200m of ascent in altitude
• Mountain summits are colder than valley floors
• Rarely there can be a temperature inversion
• Temperatures can drop suddenly
• Extremes of heat carry danger

WIND-CHILL EFFECT

• Wind Chill lowers the temperature more

• Loss in °C = approx 1/2 x Wind Speed

RAINFALL

• Rain drops can fall at speeds of ≤ 22 mph
• Rain starts off as ice or snow crystals at cloud level
• Light rain = ≤ 0.1" Heavy rain = ≥ 0.3" inches per hour
• Rain drops size = 0.02 to 0.031 inches
• Rain is recycled water that evaporated from our world's lakes, rivers, oceans, seas, waters

MIST / FOG

• Mist = mass of fine droplets of water in the atmosphere near or in contact with the earth
• density and wetness varies
• Dense Mist = Fog obscuring visibiliy further
• visibilitiy varies and can be as little as 5m

SNOW

• snow = made up of ≥ 200 frozen ice crystals
• crystals are 6-sided, all unique in size & shape
• snow forms clouds where temperature < freezing
• texture of snow varies: soft to hard, binding or loose

ICE

• water freezes to become ice at 0°C (32°F)
• ice varies in thickness from a thin sheet to inches
• a lake's surface is the first bit to freeze

ELECTRICAL STORMS

• Thunder clouds can build up static charge
• Lightning = atmospheric discharge of electricity
• Bolt can travel at 60,000 m/s (220,000 km/h)
• Lightning temperature = ≤ 30,000°C (54,000°F)
• Thunder = sonic shock wave made by lightning
• Time-lag of flash to thunder = distance of storm
• 2.9 secs time-lag = 1 km distance away