Geography Topic
Elements of weather
- Read notes
- Flashcards
- Quiz
- Confident
Study focus - 3 things
- Weather is short-term atmospheric conditions; climate is the long-term average over many years
- The 7 main elements: temperature, precipitation, humidity, wind, air pressure, cloud cover, sunshine
- Each element has its own instrument — learn which measures which
Section 1Weather vs climate
Weather is the state of the atmosphere right now or in the short term (today, this week). Climate is the long-term average pattern of weather over many years (typically 30+) for a place. "Today is rainy" is weather. "Jamaica has a tropical climate" is climate.
Section 2Temperature and humidity
Temperature — how hot or cold the air is, measured in degrees Celsius (°C) with a thermometer. Humidity — the amount of water vapour in the air, measured as a percentage with a hygrometer. High humidity (above 70%) makes hot days feel even hotter.
Section 3Precipitation and wind
Precipitation — any water falling from the sky: rain, snow, hail, sleet. Measured with a rain gauge in millimetres. Wind — moving air. Wind SPEED is measured with an anemometer; wind DIRECTION is measured with a wind vane (named for the direction it comes FROM, e.g. an "easterly" wind blows from the east).
Section 4Air pressure
Air pressure — the weight of the atmosphere pressing down on Earth's surface. Measured with a barometer in millibars (mb) or hectopascals (hPa). LOW pressure usually brings cloudy, stormy weather. HIGH pressure usually brings clear, dry weather. This is one of the most common exam mix-ups.
Section 5Cloud cover and sunshine
Cloud cover — how much of the sky is covered by clouds. Measured in oktas, on a scale of 0 (totally clear) to 8 (totally overcast). Sunshine — hours of direct sunlight during the day, measured with a sunshine recorder (e.g. Campbell-Stokes recorder, which burns a line on a card as the Sun moves).
Examples
On a hot day in Kingston, the thermometer reads 32°C and the hygrometer reads 85%. Why does it feel so much hotter than 32°C should feel?
High humidity (85%) reduces the body's ability to cool itself through sweating, because the air is already saturated with water vapour. The actual temperature is 32°C, but the perceived temperature ("feels-like") is much higher.
The barometer is falling and clouds are increasing. What kind of weather is likely on the way?
Falling pressure plus growing cloud cover signals an approaching storm or rain. Low pressure brings unsettled weather. High pressure brings clear, dry weather — the opposite.
Now let's water it
Session runs notes to flashcards to quiz back-to-back.