# TimeTree HD vs Atmospheric Model

The clearest difference is rating: Atmospheric Model at 5.0 against TimeTree HD's 1.0. Atmospheric Model also leads on review sentiment (100% vs 63%) and device support (3 vs 1). TimeTree HD's advantage is iOS requirement (8.0 vs 12.0). On price, ratings volume, update cadence and ads there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Atmospheric Model holds the better App Store score, 5.0 against 1.0. Both are backed by a comparable volume of ratings — 1 and 1 respectively. Written reviews point the same way: 63% of TimeTree HD's written reviews are positive against 100% of Atmospheric Model's.

TimeTree HD ships an update every 23 months, Atmospheric Model every 36 months. The most recent releases landed on October 7, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | TimeTree HD | Atmospheric Model |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [1.0 (1 ratings)](https://appshunter.io/ios/app/timetree-hd/id468820058/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/atmospheric-model/id1299565883/reviews)** |
| Number of ratings | 1 | 1 |
| Positive reviews | 62.5% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 23 months** | Every 36 months |
| Monetization | Free | Free |
| Size | 66 MB | 12 MB |
| Requires iOS | **8.0** | 12.0 |
| Devices | iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Arizona and Penn State Universities](https://appshunter.io/developer/372842503) | [Richard Loda](https://appshunter.io/developer/1291794366) |

## What reviewers say

### TimeTree HD

[App page](https://appshunter.io/ios/app/timetree-hd/id468820058)

Explore the evolutionary timescale of life with this app. It provides a public knowledge base of divergence times among thousands of organisms, drawing from scientific literature. Easily search for comparisons between species and view summary statistics.

**Highlights:** Explore evolutionary timescale, Thousands of divergence times, Tree-based hierarchical system, Search for organism comparisons, Compute summary statistics, Data from 2,274 studies

**Features:** macOS Compatibility

**In-app purchases:** none


### Atmospheric Model

[App page](https://appshunter.io/ios/app/atmospheric-model/id1299565883)

Explore planetary atmospheres with a radiative transfer model. Calculate emission temperatures and flux densities, then modify parameters like albedo and solar constant to simulate atmospheric changes and their effects on climate.

**Highlights:** Radiative transfer model for planetary atmospheres, Calculates emission temperature and flux densities, Adjustable parameters: albedo, distance from sun, extinction coefficients, Supports 9 solar system planets or custom planets, Generates flux diagrams of incoming and outgoing radiation, Saves and compares two model run results, Exports data to CSV for spreadsheet analysis

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is TimeTree HD free?

TimeTree HD is free to download, with no in-app purchases.

### Is Atmospheric Model free?

Atmospheric Model is free to download, with no in-app purchases.

### Which has better reviews, TimeTree HD or Atmospheric Model?

Atmospheric Model is rated higher. TimeTree HD averages 1.0 out of 5 from 1 ratings, while Atmospheric Model averages 5.0 from 1 ratings.

### Do TimeTree HD or Atmospheric Model have ads?

Neither TimeTree HD nor Atmospheric Model shows ads.

### Which is updated more often, TimeTree HD or Atmospheric Model?

TimeTree HD ships an update every 23 months, and Atmospheric Model every 36 months. Most recently, TimeTree HD was updated on October 7, 2026 and Atmospheric Model on October 10, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*