Atmosphere Notes

Temperature - is the average motion of the molecules of a substance (measured with a thermometer) There are 3 different temperature scales: –Fahrenheit – used to record surface temp in US –Celsius – used overseas & upper air obs. –Kelvin – used in scientific formulas Atmosphere Vocabulary

 Humidity- is the amount of water vapor in the air. is the amount of water vapor in the air.  There’s several ways to measure humidity, but the most useful for meteorologists is the dew point  Dew point temperature is the temperature at which the air would become saturated (and condensation would begin forming)  High relative humidity occurs when the temperature is close to the dew point Atmosphere Vocabulary

 Atmospheric pressure - is the force per unit area exerted against a surface by the weight of the air above it. (measured by barometer) is the force per unit area exerted against a surface by the weight of the air above it. (measured by barometer) Atmosphere Vocabulary

 Barometer – An instrument that measures the changes in our air pressure. –2 Types  Mercury –Consists of a glass tube open at bottom and partially filled with mercury.  Aneroid –Air tight metal box; smaller than mercury and doesn’t contain a liquid. Atmosphere Vocabulary

Barometer

 Wind – Caused by the uneven heating and differences in air pressure in the atmosphere Caused by the uneven heating and differences in air pressure in the atmosphere  Because of the Coriolis force winds in the Northern Hem: –blow counterclockwise (or cyclonically) around Low Pressure –And blow clockwise (or anti-cyclonically) around High Pressure Atmosphere Vocabulary

 Wind has 2 different measurements (speed and direction)  Wind speed is measured with an anemometer  Wind direction is measured with a wind vane Atmosphere Vocabulary

 Wind speed can be measured in mph, knots, or meters per second  1 knot = 1.15 miles per hour  1 m/s = 2.24 miles per hour  Wind Direction tells us FROM WHERE the wind is blowing  Ex: A SW wind means wind is FROM SW Atmosphere Vocabulary

 Atmosphere – Layer of gases that surrounds the planet  Composed of: Nitrogen – 78% Nitrogen – 78% Oxygen – 21% Other Gases – 1% Argon, CO 2, water vapor Argon, CO 2, water vapor Solids, pollution, dust, salt Solids, pollution, dust, salt

 Altitude –(elevation) distance above sea level –As altitude increases, temperature and air pressure decrease. –↑. ↓ ↓ A l t i t u d e t e m p e r a t u r e a i r p r e s s u r e ( d e n s i t y )

Density Density  8 km above sea levelat sea level Air is less dense as Air is most dense altitude increases; at sea level fewer O 2 molecules … …… ….. …

Layers of the Atmosphere  Troposphere –Weather here  Rain, snow, storms & most clouds found here –Clouds here  Contain 90% of air’s mass –½ mile rise in altitude  6°F drop in temperature –Height  0 – 11 km (0-7 miles)

Layers of the atmosphere  Stratosphere –Altitude  11 to 50 km (7 – 31 miles) –Ozone  Prevents skin cancer; absorbs UV rays (Ultraviolet rays)  Being destroyed by pollution; air cond. & aerosol cans  Ozone is a form of O 3 –Temperature  -60°C at lowest level and then rises

 Mesosphere (middle)  Altitude –50 to 80 km (31-50 miles)  Clouds –Are ice crystals  Temperature – -90°C (Brrr!) –Coldest part of atmosphere  Meteors burn up here –Shooting stars Layers of the atmosphere

 Thermosphere (heat)  Altitude –Above 80 km (air is very thin)  Temperature –Up to 2000°C (very hot, but doesn’t feel hot)  Ionosphere (part of thermosphere) – km (reflect radio waves back to Earth) –Aurora borealis (Northern lights)  Exosphere –550 km and outward –Outermost layer where satellites are located