Year 7 Cambridge Geography Formula & Theorem Quick Reference Handbook | 剑桥七年级地理公式定理速查手册

📚 Year 7 Cambridge Geography Formula & Theorem Quick Reference Handbook | 剑桥七年级地理公式定理速查手册

This handbook brings together all the essential formulas, calculations and key geographical rules you need for the Cambridge Year 7 Geography course. From map skills and gradient to population data and climate statistics, you can quickly find clear definitions, worked examples and helpful tips in one place. Mastering these tools will strengthen your fieldwork analysis and exam performance.

本手册汇集了剑桥七年级地理课程所需的所有核心公式、计算方法和关键地理规律。从地图技能、坡度计算到人口数据和气候统计，你可以在一个地方快速找到清晰的定义、计算示例和有用的提示。掌握这些工具将提升你的实地考察分析能力和考试成绩。

1. Map Scale | 地图比例尺

Map scale describes the relationship between a distance measured on the map and the corresponding actual distance on the ground. It is usually shown as a ratio, a fraction or a linear scale bar. The formula to find real-world distance is:

地图比例尺描述的是地图上测量的距离与对应的实际地面距离之间的关系。它通常以比、分数或直线比例尺的形式给出。计算实地距离的公式为：

Actual Distance (cm or m) = Map Distance (cm) × Scale Factor

For example, on a 1:50 000 map, 1 cm on the map represents 50 000 cm (or 500 m) on the ground. If you measure 4 cm between two points, the real distance is 4 × 50 000 = 200 000 cm, which is 2 km.

例如，在一幅 1:50 000 的地图上，图上 1 cm 代表地面 50 000 cm（即 500 m）。如果测量两点之间的图上距离为 4 cm，则实际距离为 4 × 50 000 = 200 000 cm，即 2 km。

2. Measuring Straight-Line Distance | 测量直线距离

When using a linear scale bar, place a piece of paper along the straight route, mark the start and end points, then align it with the scale to read the distance directly. With a ratio scale, multiply the map distance by the denominator and convert to kilometres or metres.

使用直线比例尺时，将一张纸沿着直线路径放置，标出起点和终点，然后将其与比例尺对齐，直接读取距离。使用数字比例尺时，将图上距离乘以分母，然后换算成千米或米。

Real Distance (km) = [Map Distance (cm) × Scale Denominator] ÷ 100 000

The factor 100 000 converts centimetres to kilometres. Always check the units: if your result needs to be in metres, divide by 100 instead.

系数 100 000 是将厘米转换为千米。始终检查单位：如果需要以米为单位，则除以 100。

3. Calculating Area on a Map | 计算地图上的面积

Area on a map is often estimated using grid squares. On a topographic map with a known grid size, you count the number of full and partial squares covered by the feature. The formula is:

地图上的面积通常利用网格方格来估算。在已知网格大小的地形图上，数出该地物所覆盖的完整方格的数目和不完整方格的折算数目。公式为：

Area on Ground (km²) = Number of Grid Squares × Area Represented by One Square

For instance, on a 1:50 000 map, a 2 cm × 2 cm grid square represents 1 km². If a lake covers 3 whole squares and about 2 half squares (equivalent to 1 whole), the total is 4 squares, giving an area of 4 km².

例如，在 1:50 000 地图上，一个 2 cm × 2 cm 的网格方格代表 1 km²。如果一个湖泊覆盖了 3 个完整的方格和大约 2 个半方格（折合 1 个完整方格），总共就是 4 个方格，则面积为 4 km²。

4. Gradient (Slope) | 坡度

Gradient measures the steepness of a slope. It is the ratio of the vertical rise to the horizontal run between two points, often expressed as a fraction or a ratio such as 1:10.

坡度用来衡量斜坡的陡峭程度。它是两点之间的垂直升高与水平距离的比值，通常以分数或比的形式表示，如 1:10。

Gradient = Vertical Rise (m) ÷ Horizontal Distance (m)

To simplify the ratio, divide both values by the vertical rise so that the rise becomes 1. For example, if a road climbs 20 m over a horizontal distance of 400 m, the gradient is 20 ÷ 400 = 0.05, expressed as 1:20.

为简化比值，将两者同时除以垂直升高，使升高变为 1。例如，如果一条道路水平距离 400 m 上升了 20 m，则坡度为 20 ÷ 400 = 0.05，表示为 1:20。

5. Vertical Exaggeration on Cross-Sections | 剖面图上的垂直夸大

A cross‑section often uses a vertical scale that is larger than the horizontal scale to make relief features easier to see. Vertical exaggeration (VE) describes how much the vertical scale has been stretched compared with the horizontal scale.

剖面图通常使用比水平比例尺更大的垂直比例尺，以便更容易看出地形起伏。垂直夸大（VE）描述的是垂直比例尺相对于水平比例尺被放大了多少倍。

Vertical Exaggeration = Vertical Scale ÷ Horizontal Scale

If the horizontal scale is 1:50 000 and the vertical scale is 1:10 000, then VE = (1/10 000) ÷ (1/50 000) = 50 000 ÷ 10 000 = 5. The height has been exaggerated 5 times. A VE of 1 means no exaggeration.

如果水平比例尺为 1:50 000，垂直比例尺为 1:10 000，则 VE = (1/10 000) ÷ (1/50 000) = 50 000 ÷ 10 000 = 5。垂直高度被夸大了 5 倍。VE 为 1 表示没有夸大。

6. Population Density | 人口密度

Population density tells us how crowded an area is. It is calculated by dividing the total population by the total land area.

人口密度告诉我们一个地区的拥挤程度。它由总人口除以陆地总面积计算得出。

Population Density (people/km²) = Total Population ÷ Area (km²)

For a country with 5 million people living in an area of 100 000 km², the density is 5 000 000 ÷ 100 000 = 50 people per km². This value helps geographers compare the concentration of population between different regions.

对于一个拥有 500 万人口、面积为 100 000 km² 的国家，人口密度为 5 000 000 ÷ 100 000 = 50 人/km²。这一数值帮助地理学家比较不同地区之间的人口集中程度。

7. Birth Rate and Death Rate | 出生率和死亡率

The crude birth rate and crude death rate are expressed as the number of births or deaths per 1 000 people in a single year. These are fundamental measures of demographic change.

粗出生率和粗死亡率以一年内每 1 000 人中的出生人数或死亡人数来表示。这些是衡量人口变化的基本指标。

Birth Rate (‰) = (Number of Live Births ÷ Total Population) × 1 000

Death Rate (‰) = (Number of Deaths ÷ Total Population) × 1 000

If a town has a population of 50 000 and records 600 births in a year, its birth rate is (600 ÷ 50 000) × 1 000 = 12 per 1 000 (12‰). Similarly, if there were 400 deaths, the death rate would be 8‰.

如果一个城镇有 50 000 人口，一年内有 600 名婴儿出生，那么其出生率为 (600 ÷ 50 000) × 1 000 = 12‰（每千人 12 人）。同样，如果有 400 人死亡，死亡率就是 8‰。

8. Natural Increase Rate | 自然增长率

Natural increase is the difference between the birth rate and the death rate. It shows whether a population is growing or declining without considering migration.

自然增长是出生率与死亡率之间的差值。它显示在不考虑人口迁移的情况下，人口是在增长还是减少。

Natural Increase Rate (‰) = Birth Rate (‰) − Death Rate (‰)

The result is usually given per 1 000, but it can also be expressed as a percentage by dividing by 10. Using the figures above (12‰ − 8‰) gives a natural increase of 4‰, or 0.4% per year.

结果通常以每千人表示，也可以通过除以 10 转换为百分比。使用上述数据（12‰ − 8‰），自然增长率为 4‰，或每年 0.4%。

9. Mean Temperature and Temperature Range | 平均气温和气温较差

Climate graphs display monthly temperatures. The mean annual temperature is calculated by adding all 12 monthly averages and dividing by 12. The annual temperature range is simply the difference between the hottest and the coldest monthly means.

气候图显示各月气温。年平均气温的计算方法是将 12 个月的平均气温相加再除以 12。年气温较差就是最热月与最冷月平均气温之间的差值。

Mean Annual Temperature (°C) = Sum of 12 Monthly Means ÷ 12

Annual Temperature Range (°C) = Hottest Month Mean − Coldest Month Mean

A location where January averages −5 °C and July averages 25 °C has an annual range of 25 − (−5) = 30 °C. A small range usually indicates a maritime climate, while a large range suggests a continental location.

如果一个地方一月平均气温为 −5 °C，七月为 25 °C，那么年较差为 25 − (−5) = 30 °C。较差小通常表明是海洋性气候，而较差大则表明地处内陆。

10. Total and Average Rainfall | 总降雨量与平均降雨量

Rainfall is measured in millimetres (mm). The total annual rainfall is the sum of all 12 monthly rainfall totals. The mean monthly rainfall helps identify wet and dry seasons.

降雨量以毫米（mm）为单位测量。年总降雨量是 12 个月降雨量的总和。月平均降雨量有助于识别干湿季节。

Total Annual Rainfall (mm) = Sum of Monthly Rainfall Totals

Mean Monthly Rainfall (mm) = Total Annual Rainfall ÷ 12

If a city receives 1 200 mm of rain in a year, the mean monthly rainfall is 100 mm. When reading climate graphs, notice that months above this average are often the wet season, while months below are the dry season.

如果一个城市一年降雨量为 1 200 mm，那么月平均降雨量为 100 mm。阅读气候图时，注意高于此平均值的月份往往是雨季，低于它的月份则是旱季。

11. Longitude and Time | 经度与时间

The Earth rotates 360° in 24 hours, so it turns 15° of longitude every hour. This is a fundamental geographic theorem that links location with time. Places east of the Prime Meridian are ahead of Greenwich Mean Time (GMT), while those west are behind.

地球每 24 小时自转 360°，因此每小时转过 15° 经度。这是一条将位置与时间联系起来的基本地理定理。本初子午线以东的地方比格林尼治标准时间（GMT）早，以西的地方则晚。

Time Difference (hours) = Difference in Longitude (°) ÷ 15

For every 1° of longitude you travel east, local time becomes 4 minutes ahead. If a city is at 45°E and GMT is noon, the local solar time is 45 ÷ 15 = 3 hours later, so it is 3:00 pm. This rule is used to understand time zones and jet lag.

每向东移动 1° 经度，地方时就提前 4 分钟。如果某城市位于 45°E，且 GMT 为中午 12 点，那么当地的太阳时就是 45 ÷ 15 = 3 小时之后，即下午 3 点。这一规则用于理解时区与时差反应。

12. Drainage Density | 河网密度

Drainage density measures how closely spaced the streams and rivers are in a drainage basin. It is the total length of all streams divided by the area of the basin. A high drainage density often indicates impermeable rock or high rainfall, while a low value suggests permeable ground.

河网密度衡量的是流域内河流与溪流的密集程度。它是所有河流总长度除以流域面积。高河网密度通常表明岩石不易透水或降雨丰富，而低值则说明地面透水性好。

Drainage Density (km/km²) = Total Stream Length (km) ÷ Drainage Basin Area (km²)

If a basin has an area of 50 km² and the total length of all streams within it is 150 km, the drainage density is 150 ÷ 50 = 3 km/km². Geographers use this index to compare landscapes and predict flooding potential.

如果一个流域面积为 50 km²，内部河流总长为 150 km，则河网密度为 150 ÷ 50 = 3 km/km²。地理学家利用这一指数来比较不同景观，并预测洪水发生的可能性。

Published by TutorHao | Geography Revision Series | aleveler.com

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