Meteorology is the study of weather, weather phenomena, and weather forecasting. It uses two kinds of observations: Qualitative: not based on numbers (hot, cold, cloudy) Quantitative: based on standardized units or conventions (wind chill, humidity, temperature) Weather is a description of the current conditions. Climate: average weather conditions over time, as determined by many decades of meteorological observations or data.

Explain the composition of gases in Earth’s atmosphere. Describe the basic structure of our layered atmosphere,including the troposphere and stratosphere.

Weather is the interaction between atmosphere and hydrosphere (air and water). Air is a mixture of many things: 1. Permanent gases - amounts that don’t change much. 78 % nitrogen gas (N 2 ) 21 % oxygen gas (O 2 ) % carbon dioxide (CO 2 ) 1% Other gases

2. Variable gases - amounts that change constantly. Most important - water vapour: 0  7% 3. Aerosols – small particles flying around. (salts, ash, dust, pollution, pollen)

≈ 12 km THERMOSPHERE STRATOSPHERE TROPOSPHERE MESOSPHERE ≈ 50 km ≈ 80 km Layers of the Atmosphere

1.Troposphere - ground level to 12 – 15 km high. Where weather takes place. Most clouds occur in the troposphere. The temperature of the air changes with altitude – It usually decreases with higher altitudes. World temperature of ground: 17ºC Average temperature at 14 km: -52ºC

Air pressure also decreases with altitude. Measures the amount of gas molecules. Average pressure at ground: kPa Average pressure at 14 km: 10 kPa Troposphere contains 75 % of air mass on Earth.

2.Stratosphere - 14 km to 50 km Contains the ozone layer (O 3 ) – 1 cm thick Air pressure continues to decrease. But temperature increases from –52º C to –3º C. Harmful Ultraviolet (UV) radiation from Sun is absorbed by the O 3 – increases temperature.

3. Mesosphere - 50 to 80 km Continued pressure and temperature decreases. 4. Thermosphere - 80 to 500 km Aurorae borealis (northern lights) in lower part. Space shuttles, satellites, space stations. Beyond – exosphere (space) Contains NO air molecules (vacuum)

Hydrosphere - all solid, liquid, and gaseous water 71 % of surface is covered by water. P Potable water – means ‘drinkable’ without having to treat it.

Caspian Sea

Amazon R.

Congo R.

Humidity Amount of water vapour (gas) held in the air. Water evaporates (liquid to gas) at all temps. The amount of water that evaporates depends on the pressure and temperature of the surrounding air.

Water vapour sticking together - clouds. The observation of clouds provides excellent weather forecasting information. Groups get bigger / heavier – rain.

Common cloud types in the troposphere: cumulus (white, puffy), stratus, and fog High in stratosphere: only thin, wispy cirrus clouds. Clouds influence the amount of heat and light that we receive every day.

The storm clouds common to Manitoba summers (cumulonimbus clouds) can carry very large moisture content. These are heavy rain and hail clouds that extends high into the troposphere.